A 44-year-old man was taken into custody Friday after stabbing four people aboard an Amtrak train traveling from Chicago, police said.

Niles, Mich. Police Chief Jim Millin told the South Bend Tribune that police received a dispatch call from Amtrak in Chicago around 7 p.m Friday after multiple passengers reported a suspicious person aboard Train 364 heading towards Port Huron. By the time police arrived at the Niles station, the attack was already underway.

One woman and three men, including an Amtrak conductor, suffered stab wounds and were rushed to the hospital, the publication reported. The severity of their injuries is unknown.

The alleged suspect, Michael Darnell Williams, 44, was booked Saturday on preliminary charges of assault with intent to murder four times, according to NBC affiliate WNDU.

A witness told WNDU that Williams began his attack by stabbing a nearby male passenger before moving on to his next victim, a female.

"I was like 'Oh my God, he's punching the guy," the passenger reported. "I saw him bring his fist back up and I noticed there was something in his fist resembling a knife blade and bring it back down."

Police subdued the attacker with a Taser before taking him into custody.

Amtrak officials are working to arrange alternate transportation for 172 passengers. Police said the investigation into the incident is ongoing. The motives behind the attack are unknown.