Passengers on a northbound Red Line train early Sunday morning say they traveled from Addison to Sheridan with one car's door wide open.
Aguilar said one passenger was partially on the train and partially on the platform when the train started to move.
"As soon as the train started moving, she started leaning out screaming, 'Hey! Hey! The door is open! The door is open!' and banging on the side of the train," recalled passenger Mark Lebeau.
It soon became clear to the passengers, they said, that the Chicago Transit Authority operator was unaware the door was stuck open.
Both Aguilar and Lebeau say the emergency call button in the train car was depressed multiple times.
"A guy across from me pressed it, and the green light comes on, and nothing," Aguilar said. "(He) pressed it again (and the) green light comes on. We're like, 'Hello? Hello?'"
A CTA employee finally closed the door when the train reached Sheridan.
No one was injured, but passengers said the experience was frightening.
"It was a little bit panicked at first," Lebeau said. "Once the emergency call button was hit and we saw a CTA worker people calmed down. And the fact that she was able to get backed away from the door, and everybody knew that she was going to be safe, I think everybody else -- people started to calm down, but at first it was panic."
The president of the union which represents CTA rail operators told the Chicago Sun-Times that he wasn't surprised to hear about the incident.
"Those doors don't work properly," Robert Kelly told the newspaper. "This is scary."
The CTA late Tuesday confirmed the incident, which comes less than two weeks after a woman said a Red Line train trapped her baby's stroller in the door at Morse, throwing her baby onto the gravel near the tracks. That incident remains under investigation.
The operator and another CTA employee on board are being interviewed and the train has been removed from service for testing. The authority says the doors on the trains are tested at least once every 40 days.