A spokesman for the Port Authority of New York and New Jersey, which operates the station, said four people were injured when the escalator malfunctioned shortly after 9 a.m. at the Exchange Place PATH station in Jersey City.
At least one person was taken to the hospital, but the extent of the injuries was not known, spokesman Ron Marsico said.
Nick Lukish, of Brooklyn, N.Y., said he was headed to work and midway up the escalator when the moving staircase started going down.
"There was a stampede at the base of the escalator," Lukish told The Associated Press. "People started to panic and yell and scream, and I saw some people jump over to the down side of the escalator, so I jumped."
The 33-year-old, who works in information technology at a bank in Jersey City, said it wasn't until he got to work that he noticed he had cuts and bruises on his shins from the jump. After going to a pharmacy to get some bandages, he returned to the station to give his account to police.
A YouTube video showed some people jumping onto the divider between the up and down escalators as others shouted in alarm or tried to keep walking up.
Two of the station's three escalators were shut down after the incident, forcing thousands of commuters to walk up the 128 stairs to the street.
The Exchange Place station suffered extensive damage during Superstorm Sandy, though it wasn't known whether any residual effects from the flooding might have caused Monday's malfunction.