A South San Francisco gym member has been booked into the San Mateo County Jail for murder after allegedly beating another gymgoer to death with some of the gym's equipment, police said Thursday night.

According to a press release sent by the South San Francisco Police department, 46-year-old Kenneth Osako allegedly took "a solid steel bar, normally used to lift weights" and bashed another person who was working out at the Bally Total Fitness at 180 El Camino Real "on his head several times" at 9:30 p.m. on Wednesday night.

After the attack, "Osako dropped the steel bar and left the scene," South SF police said.

A desk worker at the Bally's tells the Chron that Osako was frequenly jealous of other members of the gym, and that in this case the dispute might have been over a woman.

"I think he saw the other guy talking to her, flirting with her, and I think he got really angry, came up from behind and hit him in the head with a bar we use for tricep dips," he told the Chron.

(SFist gymgoers at this point are probably wondering "hey, can't you only do dips on a stationary machine?" That's correct. Tim Ehhalt, a long-time personal trainer and this correspondent's spouse, offers this insight: "I think that maybe the Bally's guy was upset and made a little glitch when he was talking to Henry (Lee, the Chron reporter). If it was a bar, I think the Bally's guy meant 'tricep extensions,' in which case an E-Z Curl bar might have been the weapon." Citing the ongoing investigation, the South SF police could not confirm the exact weapon to SFist.)

The victim of the beating was taken to San Francisco General Hospital, where he died Thursday.

Meanwhile, Osako, who police say was employed as a plumber, was tracked down by South SF police and "a special agent from the Department of Homeland Security" and was arrested Thursday morning.

Police won't say why Homeland Security was involved in the arrest, which is certainly curious. Osako is being held without bail, and is expected to appear in San Mateo County court on Monday.

[SF Chronicle]