WALSH, Colo. (AP) -- About 30 homes in a small southeastern Colorado town remain evacuated because of an ammonia spill.

A tank holding about 1,000 gallons of anhydrous ammonia fell off a trailer as it was being hauled to a farm near Walsh on Wednesday. The fall ruptured the tank, releasing an unknown amount of ammonia which turned into vapor. An unknown amount of liquid ammonia remains in the tank and crews are figuring out the best way to plug the rupture and move the tank out of town.

Anhydrous ammonia is used as a fertilizer. Riley Frazee, a spokesman with the Colorado Division of Emergency Management, says it's common to see tanks of it being hauled around the ranching and farming community.

No injuries have been reported.

Residents could be able to return to their homes this afternoon.

Copyright 2012 The AP.