A man who had made previous threats against police set his house on fire Saturday and ambushed the first sheriff’s deputy who responded, fatally shooting the deputy and wounding another before he was killed by a police officer who lives nearby, a law enforcement official said.

Authorities don’t know why Myron May targeted his alma mater Thursday when he opened fire on students at Florida State University’s library, but they do know he thought the government was watching him and out to get him.

A Florida State University alumnus and attorney who shot three people at the school’s library early Thursday believed the government was targeting him for persecution, detailing his thoughts in a journal and in videos detectives obtained, authorities said.