Very rarely. Most are gang-related (turf-wars over drugs between biker-gangs and immigrant groupings). But a person opening up with an automatic weapon on a politically motivated target? Never before. There was a politically motivated bombing in '78, I believe, were a jewish owned travel agency got hit. That is the extent of terrorism within our borders, I believe.
The perpetrator to these two attacks were most likely the same man, who was killed by the police when they challenged him. The police had apparently acquiered his identity from a taxi driver who had picked him up when he ditched the carjacked vehicle and then delivered him at his address. The police then kept his address under close guard, and he returned there early in the morning (5 a.m.) and the rest is history. He called the taxi form his cellphone, caught on CCTV - and the taxi driver (who most certainly has a case of the heebee-jeeebeees right now) supplied the address. There was CCTV on the address, and the person was seen entering and leaving the place on the footage.