A Metro-North trail derailed Sunday morning in the Bronx.

At least four people were killed and 67 people injured, 11 of them critically, according to NBC News, citing authorities.

The victims have been confirmed as three adult males and one adult female.

The accident happened around 7:20 a.m. ET as the train was rounding a curve around 100 feet from its next stop at Spuyten Duyvil station, when five of seven cars came off the tracks, an MTA spokesman said.

The cause of the accident is not known. The National Transportation Safety Board is expected to make a statement shortly.

According to CNN: "A law enforcement official on the scene and familiar with the investigation said the train operator told investigators he applied brakes to the train, but it didn't slow down."

In a news conference, MTA Chairman Thomas F. Prendergast said that speed is one of the factors authorities plan to look at during the investigation.

Hudson Line Service has been suspended between Croton Harmon station and Grand Central, Metro-North said on its website.

Amtrak service has also been disrupted between New York City and Albany.

There was an initial report from the AP that "some cars" had gone into the water. However images from news organizations, as well as social media show multiple derailments with cars near, but not in, the water.

The train left Poughkeepsie at 5:54 a.m. and was scheduled to arrived at Grand Central at 7:43 a.m.

The accident is not related to a freight train that derailed near the same station in July, NBC News reported.

Here are some pictures of the scene and screenshots from social media.

First responders gather around the derailment of a Metro North passenger train in the Bronx borough of New York Dec. 1, 2013. AP Photo/Craig Ruttle

Out for morning walk; wondering about sirens. Metro-North derailed at Sputen Duyvil. pic.twitter.com/7EyOu6x02J

— R. P. Schwartz (@Doc_RPS) December 1, 2013

Another picture on Twitter shows a car near, but not in the water.

Photo of Metro North passenger train that derailed in the Bronx. Some cars are in the river #NBC4NY pic.twitter.com/WmK9HcKrB4 — Sheldon Dutes (@SheldonDutes4NY) December 1, 2013

Bronx 2nd Alarm Derailment Photo By: @danielcohen pic.twitter.com/ckFARvaW2r — NYC Fire Wire (@NYCFireWire) December 1, 2013