UPDATED 12/27/11 10:55 a.m.

CHICAGO (CBS) — Two people are dead after a horrible head-on collision on the city’s Southeast Side.

As CBS 2’s Susanna Song reports, as of 11 a.m., debris still remained on the side of the road from the crash on the 100th Street bridge over the Calumet River.

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Police were not speculating on the cause of the crash, which happened around 12:20 a.m. Tuesday, but a woman who witnessed it and works at the site said there are a few factors that could be to blame.

“I was in the bridge, and like I said, I heard like a, ‘Bam!’ like an explosion,” said Janet Wren, a Chicago Department of Transportation worker who is in charge of lifting and lowering the bridge. “When I looked out the window, these two cars were right here.”

Wren said she ran out and saw two cars mangled up, and could see smoke rising from the vehicles.

She said one of the passengers got out of the car and was about to call 911, but police were already pulling up.

“There was a lot of flames, smoke,” said South Chicago District Officer Stoyak.

Stoyak and his partner, Officer Mason, happened to be driving east on 100th Street when they saw the cars on fire and people trapped inside.

“They were very frantic, “Mason said. “You could see the fear on the person on the back’s face; the rear passenger.”

“People yelling, screaming – the guy in the back was screaming for his life,” Stoyak said.

Wren says she watched from a safe distance as police and fire crews cut a man out of the car.

“He appeared to be having trouble breathing. He was screaming. He was frantic. We tried to pull him halfway out the rear of the vehicle, where his legs were pinned, so that he could get enough oxygen,” a Mason said at the scene.

Police say the crash involved a BMW and a Ford Taurus. One of the cars had lost control on the bridge, and slammed into the other head-on.

“These people drive on this bridge like it’s an expressway,” Wren said. “Don’t let me go into that operation. You know how some folks get to a yellow light and speed up? That’s what they do. So the way these lanes are going, they did it where it’s two, then they come into one. And it was raining out here; snowing, so it was a little slick.”

A woman in her 20s and a man in his 50s died from their injuries at Advocate Christ Medical Center in Oak Lawn and Northwestern Memorial Hospital, respectively.

Three others were reported in stable condition at Northwestern, Christ and Stroger Hospital of Cook County. They were all reported initially in serious to critical condition.

The police Major Accident Investigation Unit is investigating.

The Sun-Times Media Wire contributed to this report.

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