The sheriff said Vargas-Rosas threatened the 36 other people on the bus last night indicating he had a weapon.
At 9:45 p.m., while the bus was in Milwaukee County, at least two passengers aboard the bus called 911 to report a man was threatening to shoot and kill passengers.
The pursuit crossed into IL and the bus eventually stopped near the exit ramp to Route 173.
Authorities ultimately used spike strips to flatten the vehicle's tires, which forced it to a stop on Interstate 94 near the IL community of Wadsworth.More news: Toronto schoolgirl attacked, hijab cut with scissors
A Greyhound spokeswoman initially said that 50 passengers were on the bus, but Schmaling told reporters Saturday that the vehicle was carrying 37 people, including the driver and the suspect. "He did comply - rather reluctantly - but he was ultimately taken into custody without incident".
Authorities identified the suspect as Margarito Vargas-Rosas, an illegal immigrant who had previously been deported to Mexico.
Multiple police agencies were on the scene and motorists are advised to avoid the area.
"The law is you see emergency lights, you pull over", Williams said.More news: Facebook Changes May Impact San Antonio Digital Marketers
Vargas-Rosas is being held on making terrorist threats, Schmaling said.
With guns drawn, police took the suspect into custody. The driver says he didn't pull over because he thought the incident was a training exercise, despite passenger's pleas for him to stop. No weapons were found on him when he was booked in the Lake County, IL jail, and officers are continuing to search the bus for any weapons.
Vargas-Rosas reportedly faces charges of felony terroristic threats and disorderly conduct.More news: Ryan: Reported '****hole' comment by Trump 'very unfortunate, unhelpful'