A catastrophic bridge collapse in Baltimore early Tuesday morning has left multiple vehicles and up to 20 people plunging into the chilly waters of the Patapsco River. The incident occurred when a container ship rammed into a support of the Francis Scott Key Bridge around 1:30 a.m., causing the steel-built structure to snap in several places and send sections of the roadway crashing into the harbor below.

Dramatic footage captured the moment the bridge warped and collapsed, with lights from vehicles visible on the road surface as it tumbled into the water. Several small explosions could also be seen during the collapse. Baltimore Fire Chief James Wallace confirmed that two people had been pulled from the waters, one in serious condition, and that authorities "may be looking for upwards of seven people" in total, though the exact number remains unclear.

"Never would you think that you would see, physically see, the Key Bridge tumble down like that. It looked like something out of an action movie," said Baltimore Mayor Brandon Scott, describing the incident as "an unthinkable tragedy."

Kevin Cartwright, director of communications for the Baltimore Fire Department, called the collapse a "developing mass casualty event" and noted that some cargo appeared to be dangling from the bridge, which spans the Patapsco River at the entrance to the busy Port of Baltimore. Sonar has indicated the presence of vehicles in the water, where temperatures hovered around 47 degrees Fahrenheit (8 degrees Celsius) in the early hours of Tuesday. A huge emergency response swung into action following the collision, with first response vehicles crowding the shoreline and divers searching the water for survivors. Photographs from the scene show debris from the bridge resting on the deck of the ship, where containers were stacked several high, with reports suggesting that some of the containers were unstable, complicating rescue efforts.

"This is a very devastating incident which these individuals have encountered so our hearts go out to each and every one of them and we will be working valiantly throughout the early morning and day to address this," said Cartwright.

The 1.6-mile (2.6-kilometer), four-lane Francis Scott Key Bridge, which opened in 1977, carries more than 11 million vehicles a year and is a major part of the road network around Baltimore. Maryland Governor Wes Moore declared a state of emergency and is working to deploy federal resources, while the FBI is also on the scene.

Ship monitoring website MarineTraffic showed a Singapore-flagged container ship called the Dali stopped under the bridge early Tuesday. Logs indicate the 300-meter vessel was en route from Baltimore to Colombo, Sri Lanka. Synergy Marine Group, which owns and manages the Dali, confirmed that the vessel hit a pillar of the bridge while under the control of two pilots and that all crew members, including the pilots, were accounted for with no reports of injuries.

As the rescue and recovery efforts continue, the Maryland Transportation Authority has advised drivers to avoid the bridge, which it called an "active scene." The cause of the collision and the full extent of the damage and casualties remain under investigation.

The Port of Baltimore, one of the busiest cargo ports in the United States, handles billions of dollars of vehicles, containers, forest products, and project cargo annually. The bridge collapse is likely to have significant implications for the city's infrastructure and transportation network, as well as the ongoing rescue and recovery efforts in the Patapsco River.