New details on the Uber driver who police say transformed into a mass killer in the middle of his shift this weekend.

The tragedy is raising some serious questions today about a topic we've covered in depth at Crime Watch Daily: Is Uber doing enough to screen drivers?

Jason Dalton, 45, is the Uber driver accused of going on a one-man murder spree in Kalamazoo, Michigan on Saturday, Feb. 20, 2016.

At his arraignment, Dalton asserted his right to remain silent. The judge ordered him held without bail.

The alleged mass killer lives here in a modest Kalamazoo house and used to work as an insurance adjuster. He has no prior criminal history.

Six people died in the shootings. Cops say Dalton randomly fired at them all while picking up passengers from the Uber app.

"Our heart goes out to the families of these individuals who were just out enjoying their life," said Kalamazoo Police Chief Jeff Hadley.

Crime Watch Daily has learned that when Dalton was arrested cops found a semiautomatic handgun inside his Chevy. And they say they believe the shell casings found at the crime scenes match that weapon.

"This was a very sad day, but it was a random act of violence that no one could plan for, that someone could wake up and decide they could do a heinous act and take others' lives," said Kalamazoo Mayor Bobby Hopewell.

Could this violence have been stopped before it happened?

About an hour before the shootings began, one woman called 911 after she saw a guy jump out of Dalton's speeding car at an intersection, leaving skid marks on the road.

The passenger who jumped out told Detroit affiliate WXYZ he bolted because Dalton was driving out of control and wouldn't let him out.

"We got maybe a mile from my house and he got a telephone call, and after that telephone call he started driving really erratically, he was running stop signs, he wouldn't stop, he kept looking at me: 'Don't you want to get a ride to your friend's house?'" said Matt Mellen. "I'm like, 'Well yeah, but I want to get there alive. We were kind of driving through medians, driving through the lawn speeding along and then finally once he came to a stop I jumped out of the car and ran away."

Matt Mellen told his fiancée, who posted Dalton's picture on Facebook with a warning: "Attention kzoo peeps!!!! This Uber driver named Jason drives a silver Chevy Equinox is not a safe ride!"

The incident raises new questions about Uber safety.

Crime Watch Daily was the first national show to warn you about the potential dangers when you tap the app.