The Francis Scott Key Bridge partially collapsed in the early hours of Tuesday morning following a ship collision, local authorities said.

The incident took place at 1:35 a.m. local time on Tuesday, and workers may have fallen into water, according to a Baltimore City police spokesperson.

“I-695 Key Bridge collapse due to ship strike. Active scene,” the Maryland Transportation Authority said on social media.

A large container ship hit the bridge overnight, and there appeared to be personnel on the crossing at the time of the incident, Baltimore Fire Department Battalion Chief Glenn Kukucka told CNBC by phone. He added that the vessel involved in the collision appeared to have sustained damage.

The Francis Scott Key Bridge carries Route 695 across the Patapsco River, southeast of the Baltimore metropolitan area.

The U.S. Coast Guard did not immediately respond to a CNBC request for comment.

“I’m aware of and en route to the incident at the Key Bridge. I have been in contact with @BaltimoreFire Chief Wallace, @GovWesMoore @JohnnyOJr, and @AACoExec. Emergency personnel are on scene, and efforts are underway,” said Baltimore Mayor Brandon M. Scott on social media.

Correction: This article has been updated to reflect that the Francis Scott Key Bridge crosses the Patapsco River.