WILMINGTON, Del. — A tractor-trailer cab crashed through a concrete barrier Friday and plunged off the Delaware Memorial Bridge into the Delaware River, authorities said.

It wasn’t clear how many people were in the cab, which was found in about 20 feet of water, according to the Delaware River Bay and Authority. Authorities had not confirmed any deaths as of Friday afternoon.

The bridge, which has a clearance of about 175 feet above the river, has two four-lane spans and connects Delaware and New Jersey. The bridge is about 70 miles northeast of downtown Baltimore.

The truck, which was heading into Delaware, crossed three lanes of traffic before striking the barrier and going into the river early Friday morning, according to the river authority.

Rescue crews and dive teams from several agencies, including the U.S. Coast Guard, were involved in the search for the cab. A barge and crane also were helping with the recovery.

The cause of the crash was under investigation.