A 44-year-old Michigan man was taken into custody by police Friday, after he stabbed four passengers aboard an Amtrak train in the town of Niles, Michigan.

According to a dispatcher at the Niles Police Department, none of the stabbing victims were killed, though authorities declined to comment on the severity of their injuries. The circumstances surrounding the stabbings have likewise yet to be revealed.

Niles Police Chief Jim Millin said that the suspect, Michael Williams of Saginaw, stabbed a female and three males, including a conductor on the train at approximately 7 p.m.

According to a Berrien County Jail spokeswoman, Williams appeared Saturday morning before a judge, who set a cash bail of $1 million. Williams is charged with four counts of assault with intent to murder, she said.

#UPDATE: Mugshot released of Michael Williams, suspect in custody for stabbing 4 people on Amtrak train last night. pic.twitter.com/MOd6HgP82J

— WSBT (@WSBT) December 6, 2014

Williams subdued on Train 364, the Blue Water line, which runs between Chicago and Port Huron, Michigan:

DEVELOPING. Chi – Det Amtrak MT @Chris__Maynard: Some man just stabbed 4 people one car away from me on the train pic.twitter.com/Z6fPtUbBfP

— Chicago Sun-Times (@Suntimes) December 6, 2014

Amtrak took to Twitter to comment on the stabbing:

We're aware of an incident onboard one of our trains. Local authorities are investigating the incident w/ support from Amtrak Police Dept.

— Amtrak (@Amtrak) December 6, 2014

The incident this evening occurred in Niles, MI and we continue to support local authorities during the investigation.

— Amtrak (@Amtrak) December 6, 2014

Amtrak Spokeswoman Kimberly Woods said the train was stopped at the Niles train station at the time of the incident. The 172 passengers on board were afforded alternate transportation.

Amtrak, the brand name of The National Railroad Passenger Corporation, began operating in 1971. Today Amtrak operates 374 trains daily on 21,300 miles of track, at speeds up to 150 mph, over more than 500 destinations in 46 states. In 2012, Amtrak served 31.2 million passengers, and saw $2.88 billion in revenue.