Every motor vehicle owned by a public or governmental agency and operated for the transportation of children to or from school or privately owned and operated for compensation for the transportation of children to or from school, provided, however, that this definition of school bus shall not be extended to include buses normally used in city transit which may be used part time for transportation of school children within such cities during some portion of the day.
Okla. Stat. tit. 47, § 1-160