JOHNSON, J.

Under the free public school system of this State the responsibility for providing and maintaining school buildings and physical plant facilities rests primarily on the local units of government; whereas the financial responsibility of operating the State-wide school system, including payment of teachers’ salaries, rests primarily on the State, with the duties of fiscal control and management being administered by and through the State Board of Education. Article IX, Section 8, Constitution of North Carolina; Chapter 115, General Statutes of North Carolina.

It is expressly provided by statute, State-wide in scope, that children living in and cared for by private institutions, like Alexander School, Inc., operated for the purpose of rearing orphan children, are considered residents of the local school administrative unit in which the institution is located, “and are permitted to attend the public school or schools of such unit . . .” G.S. 115-67.

*657 In the case at band it is noted that while the building in which the Union Mills High School is conducted is located on the campus of Alexander School, Inc., it is owned and maintained jointly by the Board of Education of Rutherford County and Alexander School, Inc., by virtue of a special act of the General Assembly. Chapter 676, Session Laws of 1945. Of. G.S. 115-88. This joint ownership of the school building no doubt has proved mutually beneficial to both local agencies. However, it is noted that the special act authorizing joint ownership of the building did not extend the scope of the decedent’s duties as high school principal under his employment by the State Board of Education.

True, the record here discloses that the local county board of education knew the deceased was serving in the dual roll as superintendent of Alexander School, Inc., and as principal of the Union Mills High School, with his entire salary being paid by the State Board of Education. Nevertheless, such permissive arrangement did not merge his duties as superintendent of the private institution with those as principal of the high school, nor extend the orbit of liability of the State Board of Education under the 'Workmen’s Compensation Act and the School Machinery Act to cover his duties as superintendent of the private institution.

As to this, it is significant that G.S. 115-370 (1951 Supplement) marks out the bounds and limits of liability of the State with respect to employees who are “paid from state school funds.” The statute expressly provides: “Liability of the State for compensation shall be confined to school employees paid by the state from state school funds for injuries or death caused by accident arising out of and in the course of their employment in connection with the state operated nine months school term.”

The expression “arising out of and in the course of their employment . . .,” as used in the foregoing section of the School Machinery Act (G.S. 115-370) carries the same meaning and calls for the same interpretation and application as does the similar expression appearing in the text of the Workmen’s Compensation Act. G.S. 97-2 (f). And, in interpreting and applying the meaning of the expression, “arising out of and in the course of the employment,” as it appears in the Workmen’s Compensation Act, it has been uniformly held by this Court that the phrases “arising out of” and “in the course of” are not synonymous but involve two ideas and impose a double condition, both of which must be satisfied in order to bring a case within the Act. Davis v. Veneer Corp., 200 N.C. 263, 156 S.E. 859; Bryan v. T. A. Loving Co., 222 N.C. 724, 24 S.E. 2d 751; Brown v. Aluminum Co., 224 N.C. 766, 32 S.E. 2d 320; Vause v. Equipment Co., 233 N.C. 88, 63 S.E. 2d 173. See also 58 Am. Jur., Workmen’s Compensation, Section 709.

The words “arising out of” refer to the cause or origin of the accident; they involve the idea of causal connection between the employment and *658 the injury, and impose the condition that an injury in order to be com-pensable must spring from or have its origin in the employment. Vause v. Equipment Co., supra; Duncan v. City of Charlotte, 234 N.C. 86, 66 S.E. 2d 22; Matthews v. Carolina Standard Corp., 232 N.C. 229, 60 S.E. 2d 93; Hegler v. Mills Co., 224 N.C. 669, 31 S.E. 2d 918.

The term “in the course of” relates more particularly to the time, the place, and the circumstances under which the injury occurs. Hollowell v. N. C. Department of Conservation and Development, 206 N.C. 206, 173 S.E. 603; Berry v. Furniture Co., 232 N.C. 303, 60 S.E. 2d 97; Withers v. Blach, 230 N.C. 428, 53 S.E. 2d 668; Conrad v. Foundry Co., 198 N.C. 723, 153 S.E. 266.

And in interpreting and applying the meaning of the complete expression, “arising out of and in the course of the employment,” it must be kept in mind that while an accident arising out of an employment usually occurs in the course of it, it does not necessarily or invariably do so. Bolling v. Belk-White Co., 228 N.C. 749, 46 S.E. 2d 838; Withers v. Black, supra. See also Morrow v. State Highway and Public Works Commission, 214 N.C. 835, 199 S.E. 265. Nor does an accident which occurs in the course of an employment necessarily or inevitably arise out of it. Harden v. Furniture Co., 199 N.C. 733, 155 S.E. 728; Beavers v. Power Co., 205 N.C. 34, 169 S.E. 825; Hollowell v. N. C. Department of Conservation and Development, supra; Walker v. Wilkins, 212 N.C. 627, 194 S.E. 89; Plemmons v. White’s Service, Inc., 213 N.C. 148, 195 S.E. 370; Bryan v. T. A. Loving Co., supra; Matthews v. Carolina Standard Corp., supra; Vause v. Equipment Co., supra; Bell v. Dewey Bros. Inc., 236 N.C. 280. See also 58 Am. Jur., Workmen’s Compensation, Section 210.

Therefore proof that an employee was at his place of employment and was doing his usual work at the time of the injury, without more, is insufficient to support an award of compensation. Plemmons v. White’s Service, Inc., supra; Walker v. Wilkins, supra; Harden v. Furniture Co., supra.

Here there is evidence tending to show that the deceased customarily went to his office in the high school building at night and there performed work in the regular course of his employment as principal of the Union Mills High School, such as working on records and filling out reports. The evidence further indicates that on the night in question he was in his office, and books and records were found on his desk indicating that he had been at work on them. Therefore, on the record as presented it is readily inferable that he was at the place of his employment and was about the performance of his usual duties as principal of the Union Mills High School at the time of the murderous assault. Accordingly, the record supports the finding and conclusion of the Commission that the *659 fatal shooting occurred “in the course of” the deceased’s employment as principal of the Union Mills High School.

The mooted question is whether there is any evidence to support the finding and conclusion of the Commission that the deceased came to his death as a result of an “injury arising out of . . . his employment” as principal of the Union Mills High School, i.e., whether there is any evidence of causal connection between the murderous assault and his employment as high school principal.

The Commission rightly found that the deceased was murderously assaulted by Hugh Justice “as a result of the reprimand,” and that the rule for the enforcement of which the reprimand was administered “was formulated by the Alexander School, Inc.”

However, it is manifest that this record does not support the finding that the reprimand was administered by the deceased “As principal of the high school.”

The rule to which the reprimand was addressed was designed not for the government of Union Mills High School but solely to prohibit the older boys from Alexander School, Inc., from visiting within a certain distance of the older girls’ dormitory during evening hours. It applied in no way to any of the public school students, who at the time of its application had gone home.

It is true that at certain times Hugh Justice was a student at Union Mills High School. Nevertheless, he was a patron of Alexander School, Inc., a private child care or orphanage institution. He lived in a dormitory maintained by this institution. After the close of the regular school day and with the advent of nightfall, he was subject solely to the disciplinary rules of the orphanage, and in no manner to those governing the State-supported public school system.

The finding and conclusion reached by the Industrial Commission, approved and confirmed by the court below, that the deceased in enforcing a regulation of a private institution was acting within the scope of his duties as principal of Union Mills High School is without supporting evidence or sanction of law.

In this view of the case we think it would serve no useful purpose to remand the case for further findings of fact with respect to the relationship between Alexander School, Inc., and the deceased at the time of his fatal injury. Whether or not the deceased received from Alexander School, Inc., the equivalent of compensation in the form of living quarters, transportation facilities, or the like, is not of material significance one way or the other, in view of the clear showing that the injury which caused his untimely and tragic death arose wholly and solely out of the enforcement of a regulation of a private institution, without semblance *660 of connection, in fact or in law, with the performance of bis duties as a bigb school principal employed by the State of North Carolina.

It follows from what we have said that the award below being unsupported by the requisite proof of causal relation between the deceased’s employment as high school principal and his death, the judgment below is

Eeversed.