EL CERRITO -- A naked man was arrested on suspicion of carrying a concealed weapon after telling police he had a screwdriver in his buttocks.

The man was lying on a tree stump masturbating beside a nature path near the El Cerrito Bay Area Rapid Transit station Thursday, police said.

John Sheehan, 33, of Pittsburg was initially arrested on suspicion of indecent exposure. But when asked if he was carrying anything police should know about, Sheehan mentioned the tool, said El Cerrito Detective Cpl. Don Horgan.

"You can't get much more concealed than that," Horgan said.

Officers drew their weapons and firefighters were called to the scene, but Sheehan removed a 6-inch metal awl wrapped in black electrical tape without incident.

Sheehan, who was paroled from state prison last week, was then booked into the county jail in Martinez on suspicion of parole violations, indecent exposure and one felony count of possessing a concealed weapon.

"When you're talking about an awl or an ice pick and you're dealing with somebody who's fresh out of prison, it's a weapon. That's a stabbing instrument," Horgan said.

He noted that the rear end is a common hiding place for weapons being smuggled into prison.

It was not immediately clear what Sheehan was on parole for.