With a loud screech and an enormous collision, a semitrailer truck ran into a CTA Red Line elevated train station near Chinatown shortly before 5:20 p.m. Friday, killing two people, injuring at least 21 more, and snarling evening rush-hour traffic between downtown and the South Side.

The truck appeared to be coming off the northbound Dan Ryan Expressway exit ramp when it wedged beneath the Red Line train platform on a busy intersection across from the red pagodas that form the gates to Chinatown.

As the truck crashed under the CTA overpass, it pushed "several steps" up the escalator that leads to the train platform above, said Sohail Malik, an attendant in a parking lot across from the exit ramp. Blood and shattered glass littered the sidewalk behind it.

The sound was so loud, Michael McClure was sure an "L" train had derailed. When Malik wheeled around in the parking lot booth a few feet away from him, he saw the truck, people running and smoke pouring off the truck. A CTA security guard, with blood on her face and arm, walked away leading a dog.

Chicago Fire Commissioner Raymond Orozco said 11 victims were in serious to critical condition. Another eight were in fair to serious condition, and two more were in good condition. Four people had to be cut out of the escalators, he said.

Three children were taken to the University of Chicago Medical Center in unknown condition. Two female CTA employees were in fair condition at Northwestern Memorial Hospital, while two men were in good condition at Mercy Hospital and Medical Center, a spokeswoman said. One man was in good condition at Rush-Presbyterian-St. Luke's Medical Center. The University of Illinois at Chicago Medical Center expected two victims.

The truck driver, a 51-year-old man, and three other people—a 26-year-old woman, a 14-year-old boy and an 11-year-old girl—were all at Stroger Hospital in stable condition, according to hospital spokesman Sean Howard.

He said all the victims suffered "multiple blunt trauma," but their injuries were not believed to be life-threatening.

Howard said the 26-year-old woman might be admitted to the hospital overnight, and it's possible the teens could be released.

Howard said the driver would be released into police custody Friday night. Howard said the driver was being released against doctors' advice after refusing further treatment.

At Mercy Hospital, Jessica Ruiz, 23, visited her boyfriend Cesar Ponce, 24, who was injured in the crash.

Ponce told Ruiz he was waiting at the bus stop at the bottom of the stairs when he looked up and saw the truck heading toward the stop. He was able to jump out of the way, but suffered head injures as debris flew amid the truck's impact. Ponce told Ruiz he saw several people who were waiting in the bus shelter get "swept up" under the truck.

Children crowded around from a nearby school and adults flocked from nearby CHA complexes and storefront businesses to press against police blockades, many asking about family members. A steady stream of ambulances and emergency vehicles continued to arrive at the scene, and area hospitals said they were preparing for victims.

John Mays, 14, said he was walking toward the Red Line stop to catch a train when he heard a loud screech and saw the truck barrel into the overpass.

"It was out of control," he said. It looked like the driver tried to turn, but slammed into the station instead, the boy said.

The truck driver works for Whiteline Express based in Plymouth, Mich. A company dispatcher said the company would have no comment until its safety department reopens Monday morning.

Police blocked off streets in the area. More than a half-dozen firetrucks pulled up next to the station, and firefighters could be seen lowering victims from the station in gurneys.

Denise Bridges, whose 11-year-old daughter and 14-year-old son use the station to catch a train home, heard about the collision on the radio and rushed to the "L" platform to look for them.

Police told her that her children had been in the station when the truck slammed into it below them. Both were injured and taken to the hospital. Distraught, Bridges said she had not yet been able to talk to them. Some knew even less. Liz Vance, 28, has four children who attend the National Teachers Academy, 55 W. Cermak Rd., a block from the train station. They usually catch the train after school to head home to the South Side.

Vance also was riding the Red Line home from downtown Chicago and was forced to get off at the Red Line's Roosevelt Road subway platform. Knowing her children could have been on the affected train platform, she rushed to the station.

"I'm a little worried, and the police haven't told me anything yet," Vance said.

At 6:45 p.m., a tow truck arrived to pull the tractor-trailer truck from beneath the overpass, exposing its bashed-in front end to the people assembled east of the railroad tracks. Twisted metal hung from the overpass after the truck was removed, and a strong odor wafted over the crowd.

As the sky dimmed around 7:15 p.m., rescuers erected bright white floodlights. Others already had strung green tarps over the fence separating the Chinatown parking lot at Wentworth Avenue and Cermak from the CTA platform.

A heavy rain began falling, dispersing most of the spectators, but in the harsh glare of the floodlights, firefighters could still be seen clearing debris from beneath the overpass.

Power was restored to tracks at 7:25 p.m., said CTA spokeswoman Noelle Gaffney, as a test train could be seen rolling behind her.

Damage to the train platform entrance, escalator and elevator was extensive, she said.

Martha Dittmar, a spokeswoman for the American Red Cross, said family members searching for loved ones who may have been injured could find out what hospitals they may have been taken to by calling the Red Cross at 312-729-6200.