Authorities have arrested a man who they say held 50 people hostage while aboard a Greyhound bus late Friday night.

The incident began just before 10 p.m. Central time as the bus was headed from Milwaukee to Chicago. A passenger called 911 and said a man armed with a gun had threatened to kill people on the bus, according to the sheriff’s office in Racine County, Wis., several miles north of the Illinois border.

Authorities found the bus on southbound Interstate 94 and tried to stop it, but did not until after it crossed into Illinois, the sheriff’s office said. Authorities said the bus stopped in Wadsworth, Ill., just south of the border.

Lt. Rory Zuerlein, of the Kenosha County Sheriff’s Department, told the Daily Herald that passengers left the bus after it stopped and that officers placed them in squad cars to keep them warm.

Nobody was injured, and an investigation is ongoing, authorities said.

MEDIA RELEASE On 1/12/18 at approximately 9:50pm, the Racine County Communications Center received a transferred 911…

Posted by Racine County Sheriffs Office on Friday, January 12, 2018

Authorities have released neither the suspect’s name nor his reason for holding people hostage. It also was not immediately clear how long the passengers were held, or whether the suspect simply surrendered after the bus reached Illinois. A spokesman for the Racine County Sheriff’s Office did not immediately return a call Saturday morning.

A second bus transported the passengers to their destinations, a Greyhound spokeswoman said.

Police shut down I-94 near the Wisconsin-Illinois state line until the suspect was arrested, according to media reports.

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