CHICAGO (AP) _ A tractor trailer that witnesses said didn't seem to slow down rammed into a crowded bus shelter and a Chicago Transit Authority train station during the evening rush hour Friday, killing two people and injuring more than a dozen others.

The truck smashed into the street-level bus shelter without warning, then "climbed the stairs" of the station's north stairwell around 5:20 p.m., said fire department spokesman Larry Langford.

"This is rush hour so it's bad," Langford said.

Those killed, both women, were apparently walking near the Cermak-Chinatown Red Line station on the city's South Side, Fire Department spokeswoman Eve Rodriguez said. They were dead at the scene, she said.

Twenty-one people were transported to area hospitals, said fire department spokesman Larry Langford. Eleven were in critical condition, including four children, eight adults were in stable condition and two adults were in good condition.

Witnesses said the truck didn't appear to slow down before ramming into the station's stairwell.

Elliott Reed, 30, was walking on the street when he "heard the big bang and saw the truck go right into the station."

Reed said the scene was "surreal," with eyewitnesses asking each other, "Did you see what just happened?"

The intersection has a risky reputation because the traffic lights there change quickly, 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," she said.

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

The truck's driver was treated at Stroger Hospital and released Friday night, said hospital spokesman Sean Howard.

The 51-year-old driver passed a blood alcohol test at the hospital, but refused a urinalysis test, Howard said.

Police led the man from the hospital in handcuffs, but he was not under arrest and had not been charged with anything as of Friday evening, police spokesman John Mirabelli said.

"We are talking to the driver, that is the extent of it to this time," Mirabelli said.

Police did not identify the driver.

The logo on the side of the white truck read "XTRA Lease" in red letters. A phone message left after business hours with XTRA Lease of St. Louis, Mo., was not immediately returned. The company's Web site says it leases trucks to drivers on a short-term basis.

Hazardous materials crews were brought in because the semitrailer leaked fuel, Langford said.

Most of those injured were either in the bus shelter underneath the elevated train station or in the station's stairwell, Rodriguez said.

Engineers determined there was no structural damage to the overhead station, but the stairs sustained "very 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 at the station until further notice, he said.

The station is about two miles south of downtown, blocks from the city's Chinatown neighborhood.

Associated Press writer Sophia Tareen contributed to this report.

Copyright 2008 The Associated Press.