Jumpy Disc Jockey Arrested : Crime: Radio personality Mark Thompson bounds a counter at sheriff’s station, is cited for trespassing.

The co-host of Los Angeles’ highest-rated morning radio show was arrested Saturday after he vaulted a counter at the Santa Clarita Sheriff’s Station, landing in a secured office area, Los Angeles County sheriff’s officials said.

Mark Thompson, 39, of KLOS-FM’s “The Mark and Brian Show,” was cited and released on a misdemeanor charge of trespassing, said Sgt. Rick Doan.

“I’ve been in the Sheriff’s Department for 21 years and had never seen anyone leap the counter,” Doan said. “This is a police station--it’s not a Baskin-Robbins.”

The incident began at about 3:40 p.m. after Thompson, who lives in Canyon Country, had visited a neighbor who was jailed on suspicion of driving under the influence, Doan said.

After the visit, the disc jockey was escorted into the lobby, then left the building, Doan said. A few minutes later he returned and bounded over the counter, to the surprise of a nearby deputy.

Thompson was quickly arrested without incident.

“He said he’d left something back in the lockup area that he wanted to retrieve,” Doan said. “He’d just been back in the lockup, so he knew how the procedure worked. It seems to have been a thoughtless act.”

Security at stations around the city has been heightened, sheriff’s officials said, in the wake of the Oklahoma City bombing and the ensuing wave of bomb threats against government offices, as well as an incident last September in which a deputy in the Carson sheriff’s station was wounded by a man who burst in and opened fire.

“We have serious security concerns,” Doan said.

Neither Thompson nor KLOS officials could be reached for comment.

Known for ribald conversation and racy on-air stunts, “The Mark and Brian Show” beat out controversial “The Howard Stern Show” on KLSX-FM as the most popular morning show in Los Angeles, according to figures released in January by the Arbitron rating service.

There was, however, no indication that Thompson’s acrobatics was a publicity gimmick, Doan said.