The steel frame of the Francis Scott Key Bridge sits on top of the container ship Dali after the bridge collapsed in Baltimore, Md., on Tuesday. <a href=

The steel frame of the Francis Scott Key Bridge sits on top of the container ship Dali after the bridge collapsed in Baltimore, Md., on Tuesday. / Jay Fleming

Early Tuesday morning, a part of the Francis Scott Key Bridge in Baltimore collapsed after the Dali, a nearly 1,000-foot-long container ship heading to Sri Lanka, crashed into it.

The collision launched a search-and-rescue operation as it was unclear how many people were in the Patapsco River. Officials say that eight construction workers were repairing potholes on the bridge at the time of the collapse. Two people have been rescued with one of them seriously injured. Authorities are calling it a "developing mass casualty event."

The steel frame of the Francis Scott Key Bridge sits on top of the container ship Dali after the bridge collapsed in Baltimore, Md.

The steel frame of the Francis Scott Key Bridge sits on top of the container ship Dali after the bridge collapsed in Baltimore, Md. / Jay Fleming

Baltimore Mayor Brandon M. Scott at the Maryland Department of Transportation campus near the bridge.

Baltimore Mayor Brandon M. Scott at the Maryland Department of Transportation campus near the bridge. / Tyrone Turner/WAMU

A blocked road that leads to the now-collapsed Francis Scott Key Bridge in Baltimore, Md.

A blocked road that leads to the now-collapsed Francis Scott Key Bridge in Baltimore, Md. / Tyrone Turner/WAMU

In an aerial view, cargo ship Dali is seen after running into and collapsing the Francis Scott Key Bridge.

In an aerial view, cargo ship Dali is seen after running into and collapsing the Francis Scott Key Bridge. / Getty Images

Gov. Wes Moore speaks at a news conference at the Maryland Department of Transportation campus near the bridge.

Gov. Wes Moore speaks at a news conference at the Maryland Department of Transportation campus near the bridge. / Tyrone Turner/WAMU

A resident of Riviera Beach looks towards the Francis Scott Key Bridge that collapsed after being hit by the Dali.

A resident of Riviera Beach looks towards the Francis Scott Key Bridge that collapsed after being hit by the Dali. / Carol Guzy for NPR

The steel frame of the Francis Scott Key Bridge sits on top of the container ship Dali after the bridge collapsed.<a href=

The steel frame of the Francis Scott Key Bridge sits on top of the container ship Dali after the bridge collapsed. / Jay Fleming

People in Orchard Beach look at the Dali container ship and collapsed Francis Scott Key bridge.

People in Orchard Beach look at the Dali container ship and collapsed Francis Scott Key bridge. / Tyrone Turner/WAMU

Gov. Wes Moore speaks during a news conference at the Maryland Department of Transportation campus near the bridge.

Gov. Wes Moore speaks during a news conference at the Maryland Department of Transportation campus near the bridge. / Tyrone Turner/WAMU

A view of the collapsed Francis Scott Key Bridge after a collision with the Dali, a container ship. in Baltimore, Md.

A view of the collapsed Francis Scott Key Bridge after a collision with the Dali, a container ship. in Baltimore, Md. / Jay Fleming

Local residents gather to view a cargo ship that ran into and collapsed the Francis Scott Key Bridge in Baltimore, Md.

Local residents gather to view a cargo ship that ran into and collapsed the Francis Scott Key Bridge in Baltimore, Md. / Getty Images

The Francis Scott Key Bridge collapsed after being hit by the Dali, a container ship.

The Francis Scott Key Bridge collapsed after being hit by the Dali, a container ship. / Carol Guzy for NPR

Tags: Baltimore  Key Bridge