The Francis Scott Key Bridge along I-695 in Maryland collapsed into the Baltimore harbor early Tuesday morning following a “ship strike,” Maryland transportation officials said.

A livestream of the bridge appeared to show a cargo ship colliding with a support beam, causing the bridge to break and fall into the Patapsco River. Multiple vehicles were on the bridge at the time.

Emergency crews were searching for at least seven people believed to be in the water, Kevin Cartwright, director of communications for the Baltimore Fire Department, told The Associated Press around 3 a.m. Officials have described this as a mass casualty event. There were no specific number of deceased.

“Our focus right now is trying to rescue and recover these people,” Cartwright said, calling the collapse a “developing mass casualty event.”

It is believed that a Singapore-flagged cargo ship struck the heavily-traveled bridge. The large vessel then caught fire before it sank.

The Maryland Transportation Authority said on social media that all lanes are closed in both directions and that traffic is being detoured. Later, it urged drivers to avoid the I-695 southeast corridor and to instead use I-95 or I-895.

Mayor Brandon M. Scott and Baltimore County Executive Johnny Olszewski Jr. confirmed emergency personnel were responding and rescue efforts were underway.

Cartwright said agencies received 911 calls around 1:30 a.m. that a vessel traveling from Baltimore had struck the bridge, causing it to collapse.

“This is a dire emergency,” Cartwright added.

Location where the Francis Scott Key Bridge collapsed into the Patapsco River

He said there are “some cargo or retainers hanging from the bridge” acting as hazards that are creating potentially unsafe and unstable conditions. Emergency responders are operating cautiously as a result.

“[At] 1:35 a.m., Baltimore City police were notified of a partial bridge collapse, with workers possibly in the water, at the Francis Scott Key Bridge,” a spokesperson for Baltimore Police said in a statement to Fox News.

Multiple emergency crews are on the scene assessing the damage and investigating the cause, Fox Baltimore reported.

As of 2:45 a.m., all live camera feeds for the bridge, along I-695, on the Maryland Transportation Authority website are offline.

The iconic bridge is named after Francis Scott Key, who authored the American National Anthem, “The Star-Spangled Banner.” It opened in 1977.

This report is developing and will be updated.