The incident happened Monday and involved students from Doris Intermediate School.
The Missouri Highway Patrol says two people died when their vehicle hit the back of a school bus about 50 miles east of Kansas City.
Jurors have sided with school bus manufacturers in a 2005 Missouri crash that killed two motorists and critically injured two schoolchildren.
The same type of bullet was also found in February in the hallway of the school in Belleville.
Eleven students from north St. Louis are being treated for minor injuries.
About a half-dozen students have been hospitalized after a St. Louis school bus collided with a Metro bus.
35 batteries, weighing about 100 pounds each, were taken from First Student buses in late June.
Police in Collinsville are looking for suspects who stole batteries from nearly three dozen school buses.
The batteries weigh roughly 100 pounds and can be sold for $50 apiece at a recycling center.
Parents in St. Albans picked up a video camera and tailed the bus to prove the route was longer than state law allowed.