Oakland police officers and, apparently, a SWAT team descended on Yoshi's jazz club this morning, after a former employee went postal and destroyed roughly $10,000 of equipment with a baseball bat. Sound engineer Dan Pettit was arrested for felony vandalism after he entered the club at approximately 8:45 a.m. and wreaked havoc, bludgeoning several computers and overturning furniture. Pettit refused to talk to police, but according to Trib reporter Angela Woodall, he was upset over a dispute that occurred between engineers and performers at a concert Wednesday night. The act, hip-hop artist R.O.D. , performs over pre-recorded tracks. (The Trib mistakenly referred to R.O.D. as a sign language group — he's actually most famous for the song "I Can't Stand You.") It's still unclear what caused the argument.