Law enforcement officials say a man who threatened to kill his fellow passengers on a Greyhound bus was an illegal immigrant who had been deported once already.

Here's what happened

Police say they responded to 911 calls at 9:40 on Friday night from passengers on a Greyhound bus who said that a man was threatening to shoot people after an argument.

The police gave chase to the bus, which didn't respond to their signals to pull over.

After 17 miles, the police forced the bus to stop with spike strips, but found that the driver didn't realize they were trying to get him to stop. The 36 passengers were removed from the bus, including the suspect.

The police arrested Margarito Vargas-Rosas, 33, who was living in Chicago, and charged him with making terroristic threats and disorderly conduct. Police say he continued to make threats in custody, but no gun was discovered in his possession.

Vargas-Rosas had been deported in 2012, but had returned to the United States illegally again and was working in Chicago.

"He said he was gonna kill us, said he was gonna put a bullet in our head," said one passenger. "You know, he was just acting crazy. We tried to get him to calm down... he refused to."

Here's a local news report about the incident:

Here's video of the police news conference about the incident: