STARKE, Fla. (AP) — Authorities say a naked woman was riding in the tractor-trailer that struck a school bus in north Florida, injuring 10 people.

Florida Highway Patrol Sgt. Dylan Bryan says it is unclear why the woman was not clothed when the truck hit the bus Monday afternoon. The bus was carrying elementary students to their homes.

Authorities say none of the students received life-threatening injuries, but the driver of the tractor-trailer and the woman were in critical condition.

Bradford County school officials said there were 15 students on the bus when it was hit traveling south on U.S. 301.

Bryan said the semi had a sleeper compartment. He did not know if the nude woman was in the cab or in the sleeper area when the accident occurred.

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.