WEBBERS FALLS, Okla. -- Rescue workers pulled the bodies of three people from mangled cars as divers searched for several others feared drowned in vehicles that plunged into the Arkansas River on Sunday when part of a bridge collapsed after being struck by a barge, police said.

Authorities said they were working to determine the identity of the first three confirmed victims - two women and one man - and expected to pull several more vehicles from about 11 feet (3.5 meters) of water.

The Oklahoma Highway Patrol had estimated six to 11 people were trapped and feared dead in their vehicles, which fell about 100 feet (30 meters) into the water from the interstate 40 bridge about 7:45 A.M. CDT (1245 GMT), 60 miles (95 km) south of Tulsa.

About nine vehicles plunged into the water after the captain of an empty oil barge apparently passed out at the controls after suffering a seizure and slammed into an unprotected part of the bridge, causing a 500-foot (150-meter) section to give way, police said.

Emergency workers had recovered one car, one pickup truck, one motor home and a horse trailer with three dead horses trapped inside from the accident site.

The crash cut traffic on a major east-west thoroughfare and led to a stoppage of river traffic on Oklahoma's main inland waterway.

"It sounded like an explosion," a witness told Reuters.

He said he was participating in a bass fishing tournament and there were several boats in the water at the time of the crash that helped rescue victims.

Oklahoma Gov. Frank Keating, who toured the crash site earlier, told CNN on Sunday night there was still no confirmation on the number of people killed.