The incident happened last Thursday night as Thanksgiving revelers left the Lighting of Macy's Great Tree at Lenox Square.
As dozens of people stepped onto the escalator to go down to the trains, it suddenly accelerated.
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"It happened really quick," Matt Fields told Channel 2's Richard Elliot. Fields said he was about to step onto the escalator when he saw it speed up.
"There was a loud boom," he said. "Then, it started going extremely fast and everybody was kind of dumped together. People had to jump off."
No one was injured in the incident.
Through an open records request, Channel 2 Action News obtained the surveillance video of the incident. It shows the escalator accelerating and the crowd of people on the train platform scrambling to get out of the way. It also shows MARTA police rushing quickly to the scene and hitting the emergency stop button.
MARTA spokesman Lyle V. Harris told Elliot they are conducting a full investigation into what happened, but right now they just aren't sure.
"We have not been able to figure out what went wrong," said Harris. "We are closely investigating this, trying to figure out what the malfunction was and what type of failure it was."
Harris said the Lenox station escalator will remain closed until they determine what happened and the problem is repaired.
This is not the first accident involving MARTA escalators. Two years ago, a brake system failure causes a similar acceleration on a Five Points MARTA station escalator. Fifteen people were hurt.
Earlier this year, MARTA said it fired a contractor because he bypassed an escalator security system at the Dunwoody station.