A man died after his motorized wheelchair fell down an escalator at Columbia Heights Metro station Wednesday afternoon, the transit agency said.

Metro spokeswoman Sherri Ly said that the man was using a wheelchair on the “up” escalator. She said he had nearly reached the top when he and the chair tumbled backward to the bottom.

D.C. Fire spokesman Doug Buchanan said the man was found unconscious at the bottom of the escalator, and was transported to a hospital with life-threatening injuries. He later died.

Ly said that Metro is not releasing his name, pending notification of his next of kin. His age is not known.

The station’s elevator was operating properly at the time, Ly said.

“A review of camera footage revealed the man waited 10 to 15 seconds for the elevator, which was in service at the time, and then diverted to the escalator,” Ly said. “Upon reaching the top of the escalator, the man and wheelchair fell backward, landing at the bottom.”

The video footage of the incident is not being released, Ly said.

“Several bystanders and the station manager immediately rendered aid until medics arrived,” she said. “The man was transported to a hospital where he was pronounced deceased.”

Of the major transit systems in the country, Metro is considered one of the most easily navigable for people with disabilities. Because its stations were built in recent decades — compared with stations in New York City or Boston, some of which are a century old — they are all equipped with elevators to enable people who rely on wheelchairs to use the system. And according to Metro’s most recent performance report, elevator availability for the last fiscal year, from July 2017 to June 2018, was 97 percent.

Still, people with disabilities have said that those numbers do not reflect their experience, and they become exasperated when they repeatedly encounter elevators that are not operating properly.

Some suggested on social media that perhaps the man in Wednesday’s incident had assumed that he had encountered another broken elevator.

“Incredibly tragic,” Anthony LaMesa wrote on Twitter. “This man was likely so inured to #WMATA elevators being broken that he just assumed it would never come.”

A similar incident occurred in Boston’s "T" in 2012, when a woman in a motorized wheelchair attempted to use an escalator to go to the upper level of a Red Line station. Her wheelchair made it only a few feet from the ground before it tipped over, causing her to somersault several times before she was helped by fellow passengers and a station employee who stopped the escalator.

The woman was not seriously injured, according to the Boston Globe.