Burglars ransacked offices in the headquarters of the Society for Prevention of Cruelty to Animals, stealing video recorders and three handguns. Police said the intruders apparently slipped into the two-story building at 5026 W. Jefferson Blvd. in South Los Angeles over the weekend, using a rock to smash a second-floor window at the back of the complex, then breaking into lockers to steal three handguns, a supply of ammunition and several video recorders. A silent alarm was triggered and police were immediately summoned, but the officers checked only the outside of the fenced building and found no evidence of a break-in, so the crime was not discovered for another hour. "It seems senseless," SPCA Lt. Charles Reed said. "We doubt it was animal-haters, but in a thing like this, who knows?"