CARSON, Calif. (AP) _ A wall collapsed at a construction site Thursday, trapping about 10 workers some 30 feet underground, firefighters said.

``We have approximately 10 people trapped by a cement decking that came down on top of the workers,'' Los Angeles County Fire Department Inspector Mike Brown said.

The excavation was taking place at a wastewater treatment plant, he said. He had few details.

He said he didn't know if firefighters had established communication with the workers.

The accident was reported at 8:20 a.m. Carson is about 15 miles south of Los Angeles.