SAN FRANCISCO (AP) _ A shootout between police and a fleeing gunman closed the nation's busiest toll bridge this morning, causing a huge rush-hour backup of commuters.

The gunman, whose name was not released, was critically wounded by gunshots to his face, neck and hand. Officers at the scene reported the man may have shot himself during the gun battle. A 9 mm handgun was recovered.

Westbound traffic into San Francisco began flowing on the upper deck of the San Francisco-Oakland Bay Bridge less than an hour after the 5 a.m. shutdown, but the backup of cars took several hours to clear.

All lanes of the lower deck, where the shooting took place, were reopened about 9 a.m. The bridge carries 280,000 vehicles each day.

The man was taken to San Francisco General Hospital, where spokeswoman Corinna Kaarlela said he was in critical condition.

Officers were called after reports that a man with a gun was seen on Treasure Island, a decommissioned naval base adjacent to the bridge.

Officers found a car and ran a license check, which indicated the vehicle was linked to a homicide in Texas, said police spokesman Jim Deignan.

``We haven't confirmed that it was,'' he said, adding that officers were coming from Texas.

As officers were inspecting the car, a man suddenly sprinted towards the bridge, starting a foot chase. At one point, the man tried to halt other motorists, according to homicide Lt. Dave Robinson.

Among those drivers were James Thompson, who said he saw the man fire at police and run between cars, apparently trying to stop them.

``He came at me and pointed his gun at me,'' said Thompson, who put his car in reverse to escape.