LIVERMORE -- Authorities are searching for a 30-year-old man who fell out of a kayak and disappeared at Lake Del Valle on Sunday afternoon.

The Mountain House man was with a female relative on a rented, two-person kayak when he fell into the water at Del Valle Regional Park, said Alameda County Fire Department Battalion Chief James Watkins. Fire crews were dispatched at 2:35 p.m. to the regional park at 7000 Del Valle Road.

A rescue effort that included teams in helicopters and boats searched for the man for more than three hours but did not locate him, Watkins said.

A dive team with the Alameda County Sheriff's Office is also searching for the man.

Check back for updates to this story.

David DeBolt covers breaking news. Contact him at ddebolt@bayareanewsgroup.com. Follow him at Twitter.com/daviddebolt.