Firefighters in California on Thursday night rescued a man after he became trapped waist-deep in cement for hours.

A supervisor at U.S. Pipe in Union City was looking into a concrete hopper silo when he lost his balance and fell into it, a worker told Fox 2 KTVU.

The Alameda County Fire Department said first responders performed a "technical rescue" to pull the man out of the hopper.

"He's been secured w/ a harness to prevent him from sinking deeper & crews are draining product from the bottom of the hopper to alleviate the dry cement from around the patient," the department tweeted.

The man was finally rescued roughly two hours later, around 6:45 p.m. local time.

Nicole Darrah covers breaking and trending news for FoxNews.com. Follow her on Twitter @nicoledarrah.