Gunfire erupted in the bathroom of a bus heading from Chicago to Minneapolis soon into its trip late Tuesday night, and a passenger on board reportedly subdued the man until law enforcement arrived, a bus spokesman said. No one was wounded.

The incident occurred about 11:30 p.m. on a double-decker Megabus heading to the Twin Cities, said bus spokesman Sean Hughes.

The man came out of the bathroom after the shots were fired and was met by passengers, Hughes said.

"Shots fired on the Mega Bus that I am traveling on!" passenger Kenneth Hasley Sr., of Minneapolis, said in an as-it-happens Facebook message. After three replies asking whether he was OK, Hasley said, "I am fine. We are on the side of the road."

He then messaged, "The state police took [the gunman] off the bus after he got whooped by a passenger."

The passenger who took down the gunman told WBBM-TV in Chicago that he overpowered and disarmed the man.

"He was grabbing at his hip … and I told him he was getting too close," Kenneth Smith told the TV station. "As he kept coming, that's when I rushed him. I choked him. He fell to the floor.

"The clip came [partway] out of the gun, and that's when I saw it. So I pulled it out, gave it to my cousin, and I held him down until the police came."

The driver called police and stopped the northbound bus at the Des Plaines Oasis, a food and fuel stop along Interstate Hwy. 90, where the man was turned over to police.

Hasley told WBBM that "the bus could've crashed, anything, the way the guy was aggravating the bus driver. So that guy right there [Smith] is a hero."

Illinois State Police spokesman Sgt. Matthew Boerwinkle said his agency was still trying to "confirm the identity of the suspect" as of late Wednesday morning.

Hughes said the 50 or so passengers were put on another bus "out of an abundance of caution … and continued on their journey" to Madison, Wis., and ultimately Minneapolis.

Passengers are not screened or searched for weapons, Hughes said, noting that "nobody does that [in the bus or rail industries], not even Amtrak. Obviously, we are complying with the law."

Chicago-based Megabus, known for its bright blue buses with "$1" displayed, offers express service in 120 major cities in North America from 13 hubs for fares as low as a dollar.