MONTEREY PARK (AP) — Exploding ammunition after a Southern California freeway crash shut down highway lanes for more than hour.

California Highway Patrol Officer Patrick Kimball says several vehicles collided at 9:25 p.m. Monday in the westbound lanes of State Route 60, the Pomona Freeway, in the Monterey Park area 10 miles east of downtown Los Angeles.

One of the vehicles was engulfed in flames and ammunition inside began exploding, posing a temporary threat to first-responders at the scene.

The fire was extinguished and wreckage was towed away.

City News Services says the westbound freeway lanes reopened at about 10:40 p.m.

(© Copyright 2011 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)