The John CaldwellFrancis Scott Key Bridge in Baltimore, Maryland collapsed Tuesday into the Patapsco River after it was struck by a large cargo ship.

The bridge's collapse has prompted huge emergency response, with the Baltimore City Fire Department describing the collapse as a mass-casualty incident, and rescue crews searching for seven people in the river. Maryland Gov. Wes Moore has declared a state of emergency.

Baltimore Mayor Brendon Scott said on X that he was aware of the incident and was en route to the bridge. "Emergency personnel are on scene, and efforts are underway," he said.

The 1.6 mile, 4-lane bridge named for the author of the "Star-Spangled Banner," was the second-longest continuous-truss bridge span in the United States and third in the world.

Follow here for live updates →Baltimore's Key Bridge collapses after ship collision; rescue effort underway

Photos show collapsed Francis Scott Key Bridge in Baltimore

Videos show Francis Scott Key Bridge's collapse

The bridge's collapse, which came after it was struck by a container ship, was distributed on social media.

What did the Francis Scott Key Bridge look like before it was hit?

Contributing: Charles Ventura, Thao Nguyen and Susan Miller, USA TODAY.