The parents of three victims of a deadly rampage in Santa Barbara, California, last year are suing the county, the Sheriff's Department and the apartment building where the killer lived.

Parents of David Wang, James Hong and George Chen filed the lawsuit alleging negligence in federal court Monday.

Twenty-two-year-old Elliot Rodger stabbed, shot and ran down people in the community of Isla Vista in May. He killed six UC Santa Barbara students and injured 14 other people before killing himself.

Wang and Hong were Rodger's roommates. The lawsuit alleges Capri Apartments and Asset Campus Housing failed to properly screen Rodger or warn roommates he was violent and unstable.

It also contends the Sheriff's Department deliberately ignored "red flags" that Rodger was dangerous.

Messages left with the defendants weren't immediately returned.