In Estate of Garza v. McAllen Independent School District, 613 S.W.2d 526, 527 (Tex. Civ. App.-Beaumont 1981, writ ref'd n.r.e.), a non-student passenger stabbed a student passenger on a school bus. The court of appeals held that "the injury arose out of the failure to control and supervise the public, and not from the operation or use of a motor vehicle. . . . A knife and not the use of the bus was the cause of plaintiffs' damage." Id. at 528; See also Pierson v. Houston Indep. Sch. Dist., 698 S.W.2d 377, 380 (Tex. App.-Houston 14th Dist. 1985, writ ref'd n.r.e.) (holding that student's act and not the operation or use of truck and trailer was the cause of plaintiffs' injuries).