Ambulances have rushed to the scene of a collision of two Metro-North Railroad trains in Connecticut that was caused by the derailing of one of them between Bridgeport and Fairfield Friday shortly after 6 p.m. EDT, according to the Stamford Advocate.

At least four injuries were reported by 7 p.m., Fairfield Police Department Lt. James Perez told the Advocate. They were one person with severe back pain, one person with severe neck pain and two people with unknown injuries.

“At this stage, we don’t know if this is a mechanical failure, an accident or something deliberate,” Perez said.

Because of the collision, the Metropolitan Transportation Authority posted online a special service notice: “New Haven Line Service Alert: At this time no Westbound service is being provided beyond Bridgeport due to a train incident in the vicinity of Bridgeport. Eastbound service will run to South Norwalk. As more information becomes available we will notify you as soon as possible. Please listen for announcements at your station.”

Update, 8:16 p.m.: Another 22 injuries were reported by 7:30 p.m., the Stamford Advocate said. All of these injured people have been taken to local hospitals.

Update, 9:35 p.m.: A representative of Bridgeport Hospital in Bridgeport told Reuters it had seen 22 people injured by the crash, one of whom was seriously injured, while a representative of St. Vincent’s Medical Center in Bridgeport told the news agency it had seen 27 people injured by the crash, one of whom was seriously injured. Hospital officials have been counseled to prepare to receive as many as 180 patients. Meanwhile, Amtrak took to Twitter to post this advisory:

Update, 10:15 p.m.: About 60 people have now been taken to two local hospitals, Connecticut Gov. Dannel P. Malloy said at a press conference Friday night, according to the Hartford Courant. Among them, five were seriously injured, and one was listed in “very critical” condition. Malloy also said railroad travelers should anticipate service between Bridgeport and South Norwalk will be disrupted at least through Monday.