Elliott Reed was a few moments late and was still walking toward the Chicago Transit Authority train station when a tractor-trailer rig exiting a nearby expressway abruptly veered into the busy station and a bus shelter.

The truck ended up wedged inside a stairwell leading from the street-level station to the elevated train's platform above. Two women died at the scene and at least 21 others were injured in the evening rush-hour incident, police said.

If it hadn't been for a delay at work, said Reed, a 30-year-old bank security officer, he could have been one of the victims. He said he "heard the big bang and saw the truck go right into the station."

The Chicago Police Department was still investigating the crash at the Cermak-Chinatown Red Line station on Saturday. That investigation included questioning the truck's driver, who was taken away in handcuffs after being treated at a hospital. His name was not released.

The man, 51, tested negative for blood alcohol but refused a urinalysis test, said Stroger Hospital spokesman Sean Howard.

The man was not under arrest or had been charged with anything as of late Friday, said police spokesman John Mirabelli. "We are talking to the driver, that is the extent of it to this time," Mirabelli said.

"Right now this is just a tragic traffic accident," said Deputy Chief Joseph Patterson.

Most of those injured were in the bus shelter or the train station stairwell, said fire department spokeswoman Eve Rodriguez.

The truck didn't appear to slow down before the impact, witnesses said.

The intersection has a bad reputation, said Meekus Wong, who works at a restaurant located directly in front of the train station.

"That was always a very dangerous intersection because the traffic lights switch really fast," she said.

"I was supposed to take the train. Thank God I took the bus," Wong said.

Engineers determined there was no structural damage to the overhead station, but the stairs had significant damage, said CTA President Ron Huberman. Trains on the Red Line, which runs to the city's far South Side from downtown, will not stop there until further notice, he said.

The station is about two miles south of downtown and near two major expressways, Interstate 55 and Interstate 90/94.

The logo on the side of the white truck read "XTRA Lease" in red letters. The company's Web site says it leases trucks to drivers on a short-term basis.

There was no immediate response to a call after business hours seeking comment from the company at its offices in St. Louis, Mo.

Twenty-one people were taken to hospitals, Langford said. Eleven were in critical condition, four of them children, said fire department spokesman Larry Langford.