CHICAGO - Tests so far show that doors on a CTA Red Line train were working properly when they closed on a toddler in a stroller, trapping her and dragging her along a North Side platform until she was flung alongside the tracks.

The 22-month-old girl missed the third rail and was far enough away from the train that she was not struck as the southbound train left the Morse station in Rogers Park Monday evening. She was scooped up by her mother and taken to Children's Memorial Hospital, where officials said she was not seriously injured.

The Chicago Transit Authority said the doors were checked Monday night and "appeared to be working properly."

"We are continuing to test the doors on the rail car," added the agency, which said the train has been removed from service while further tests are conducted on all of the train's systems.

Officials are also investigating why the operator did not spot the stroller stuck in the door as the train started moving. Train operators must look outside of the cab window to make sure it is OK to close the train doors before leaving a station.

They also must check signal lights located by each train door to determine that they are all closed.

Another question involves the doors themselves. Doors on CTA trains are equipped with sensors designed to automatically reopen the door if an object is caught between the doors.

The CTA did not explain how the doors could have been working properly but did not reopen when they hit the stroller.

The toddler, who witnesses said is named Rachel, remained today at Children's Memorial Hospital, where she was being held for observation.

The incident happened around 6:30 p.m. Monday. Joel Weinberg and his wife had just gotten off a train from downtown and were headed down the steps from the platform when a woman passed them carrying a stroller in her arms, running up the stairs and calling up for someone to hold the train.

"Then we heard a scream," said Weinberg, 38. "You hear a scream like that -- we stopped on the stairs and said 'That can't be good.' "

Police said the child's 26-year-old mother was pushing the stroller into the train when the doors closed and the train began moving. The stroller was dragged down the platform with the child in it and the mother hanging on.

The stroller fell on its side and the child's head bounced several times against the platform, police said.

By the time Weinberg and his wife got back to the platform, the mother was crying hysterically and yelling, "The train took my baby," Weinberg said. Then a man at the south end of the platform called to them. There was a baby on the ground.

"I was afraid to look," Weinberg said.

About 10 feet past the end of the platform, on the gravel to the left of the inside rail, he saw the child, conscious and not crying, lying on her back amidst other items knocked out of the stroller -- some groceries, bananas -- Weinberg said. The stroller was nowhere to be seen.

The mother jumped down to the ground and scooped up the girl.

Weinberg took the child and handed her to the other man, who then passed her to Weinberg's wife Rebecca. Weinberg then helped the mother back to the platform.

The child's eyes were open and she was looking around, but appeared a little dazed. She spit up a reddish substance that splattered on Weinberg's wife's clothes; they initially thought it was blood, but later found out was cough medicine, Weinberg said.

"My wife didn't sleep all night," he said. "She kept saying, 'The baby's fine, the baby's fine.' "

The mother is a caregiver who works five days a week cleaning an elderly man's Rogers Park home and running errands for him. She had left his place around 4:30 p.m. Monday and planned to rush by her workplace to drop off some paperwork before picking up her child.

Two hours later, the man got a call from the mother. "She was crying, I couldn't understand her," he said. "She said a wheel on the stroller got caught in the train."

The man says the woman is from Nigeria. He described her as a devoted mother who goes to church every day.

The child was born premature, and the mother takes Thursdays off to take the toddler in for therapy. "She's not growing," the man said, though he didn't know exactly what was wrong with the child.

"The only time she leaves the baby out of her sight is when she works," he said. "She's a very nice person, she has a very good heart. She goes to church every day. She would go out of her way for you."

At the mother's employer, a home health services company in Uptown, manager Beatrice Oyedokun said the woman called the office this morning to let her know about the accident.

She was crying. She said she spent the night replaying the events of Monday evening in her head and she still couldn't explain how it all happened.

"She's just getting herself back together," Oyedokun said.