The man accused of stabbing four passengers on an Amtrak train says he began the attack because he “saw a demon he had to fight,” according to the Associated Press (AP). The attack occurred on Friday in southeast Michigan on a train traveling with 172 passengers from Chicago to Port Huron, which is 60 miles northeast of Detroit.

Michael D. Williams, a 44-year-old military veteran from Saginaw, Mich., stabbed the conductor, a woman and two men on the train in Niles, Ind. Amtrak called the police to report a passenger acting suspiciously. When officers arrived on the scene, they found Williams with a knife in his hand and used a stun gun to gain control of the situation.

Williams told detectives that the “guy he was talking to on the train turned into a demon and he had to fight” him, according to the AP. There appears to be no motive for the stabbings and all the victims are in stable condition.

Williams’ sister, Tracey Williams, told the AP that Williams told her he was hallucinating and feared for his life. “We were having conversations back and forth, and I said, ‘You know, Mike, this doesn’t make any sense. Why are they after you?'” Tracy Williams said. “Whatever he believed in his head was real to him. Nothing I could have said could make him think any different.”

Williams was charged with four counts of attempted murder. He was arraigned on Monday and requested a court-appointed attorney. The judged issued a not-guilty plea on his behalf and ordered Williams to be sent to the Berrien County jail on a $1 million bond, according to the AP. He is due back in court on Friday.