A ship struck Baltimore's Francis Scott Key Bridge early Tuesday, causing a partial collapse and sending vehicles and people into the water, officials in Maryland said.

       "I can confirm 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," the Baltimore Police Department said in a statement.

       The Maryland Transportation Authority said the collapse occurred "due to ship strike."

       Multiple vehicles plunged from the bridge at the time of the collapse, the Baltimore City Fire Department said. Overnight work had been underway on the bridge and divers were searching for at least seven people in the water, the department said.

       The bridge, which is part of Interstate 695, crosses the Patapsco River in Baltimore’s harbor.

       "All lanes closed both directions for incident on I-695 Key Bridge," MDTA officials said in a statement at about 2 a.m. on Tuesday. "Traffic is being detoured."

       ABC News' Victoria Arancio, Alex Grainger and Sam Sweeney contributed to this story.