Truck smashes through barrier and plunges off a bridge into the Delaware River

A tractor-trailer cab plunged off the Delaware Memorial Bridge into the Delaware River near Wilmington

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.

Two four-lane spans make up the bridge that connects Delaware and New Jersey.

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.

The cause of the crash was under investigation.