The Francis Scott Key Bridge in Baltimore collapsed early Tuesday morning after it was struck by a large ship, according to video obtained by CNN.
It is unclear if anyone was injured.
Maryland Transportation Authority (MTA) says all traffic is being detoured.
CNN has reached out to Baltimore City Fire Department for additional information.
The 1.6-mile, four-lane bridge extends over the Patapsco River and serves as the outermost crossing of the Baltimore harbor and an essential link of Interstate-695, or the Baltimore Beltway.
Baltimore is facing a “mass casualty multi agency incident,” with response teams working to rescue around 20 people who may have fallen into the river when the Francis Scott Key Bridge collapsed.
“We are in the midst of managing a mass casualty multi agency incident here,” said Kevin Cartwright, director of communications of the Baltimore City Fire Department.
“Unfortunately, we understand that there are up to 20 individuals who may be in the Patapsco river as well as multiple vehicles,” he told CNN.
Cartwright said they are working with the US Coast Guard and a team of divers are in the river for search and rescue operations, with temperatures around the port at around 30 °F (-1°C).
There could have been a vehicle “as large as a tractor trailer” on the bridge at the time of collapse, Cartwright said.
The cargo ship that hit Baltimore’s Francis Scott Key Bridge was a Singaporean-flagged container ship, the DALI, according to data from a maritime monitoring site and a Coast Guard officer.
Maritime tracking website, MarineTraffic, showed the Singapore-flagged ship stopped in Baltimore, where it was departing with a destination of Colombo, Sri Lanka. It appeared stopped around 1:30 a.m. ET and was surrounded by first response boats, per the website.
It is the same time local agencies reported they received 911 calls that a large ship traveling outbound from Baltimore had struck a column on the bridge, Kevin Cartwright, spokesperson for the Baltimore Fire Department told AP.
Matthew West, a petty officer first class for the Coast Guard in Baltimore, also told the New York Times it was the DALI that struck the bridge.
The ship is around 300 meters (984 feet) long with a width of around 48 meters (157 feet), according to MarineTraffic data.
CNN has asked the Coast Guard and is attempting to contact the owner and managers of the ship.