The sheriff said Vargas-Rosas threatened the 36 other people on the bus last night indicating he had a weapon.
The bus was traveling with 50 passengers on board from Milwaukee to Chicago when the incident began around 9:50 p.m. CDT, Greyhound said in a statement.
He said the Kenosha County Sheriff's Department, Wisconsin State Patrol, and Illinois State Police all assisted in chasing the bus across the state line.
According to the Illinois State Police, troopers were responding to a "possible hostage situation" on the bus. Central time as the bus was headed from Milwaukee to Chicago.
The bus eventually stopped on I-94 at Rt. 173.More news: TRACKING: Flood Watch, Winter Weather Advisory issued for region
The Racine County sheriff said on Saturday that Vargas-Rosas is an illegal immigrant who has been deported before. "You're on a bus with a guy who said he had a gun", said Dodd. Dodd said the man pulled something out of his trousers that Dodd believed may have been a weapon.
"He was acting insane", passenger Patrick Dodd said, according to CNN affiliate WLS.
Vargas-Rosas reportedly faces charges of felony terroristic threats and disorderly conduct. "He thought it was a training exercise; he thought we were trying to stop someone else".
"The law is you see emergency lights you pull over", Williams said.
Vargas-Rosas was ordered off the bus at gunpoint, according to Fox 6, and was taken into custody without incident. "We tried to get him to calm down, there were four or five people telling him to sit back down, but he refused to, and that's when I was on the phone with 911 begging for help".