SAN FRANCISCO -- A Hayward man attempting to navigate through the dangerous S-curve of the San Francisco-Oakland Bay Bridge at a high rate of speed lost control of his rig early Monday, crashing through the guardrail and falling 200 feet to his death, authorities said.

California Highway Patrol Sgt. Trent Cross said that at about 3:30 a.m. the driver was traveling westbound on Interstate Highway 80 at high speeds, and lost control of the vehicle. The truck went over the side of the bridge and dropped about 200 feet onto Yerba Buena Island.

"Witnesses have stated that the driver was traveling at approximately 50 mph as he was approaching the S curve," Cross said. "That's too fast. When you are driving a commercial vehicle as large as a big rig that is fully loaded with a load of pears, when there is a sudden shift of weight, that vehicle will easily lose control."

The driver suffered fatal injuries was pronounced dead at the scene, CHP Officer Ralph Caggiano said.

Authorities said the driver had just refueled his rig filled with pears before entering the bridge. The impact of the crash triggered an explosion that ripped the vehicle apart.

Firefighters responded to reports of flames caused by the crash, but the fire was out by the time units arrived, according to the San Francisco Fire Department.

"When our crews got here they were amazed, they sent out the page right away," said Deputy Chief Pat Gardner. "Looking at this pile over here, the truck basically exploded and was carrying a load of produce. There are pears all over the place. It's a pretty amazing sight."

The two right lanes of the bridge's S-curve were closed on the westbound side, according to Caggiano. The CHP did not have an estimate of when the lanes might re-open.

Cross said Caltrans inspectors had examined the crash damage and determined the bridge was safe for commuters.

"There is no structural damage to the bridge," Cross said. "The bridge is safe."

The S-curve was installed over Labor Day weekend and have been the source of numerous crashes -- more then 42, according to the CHP. In an attempt to make it safer, the speed limit was lowered from 50 mph to 40 mph and flashing lights warn drivers of the curves.

Caltrans spokesman Bob Haus said the problem is drivers' speed rather than the S curve design itself.

"Nothing is wrong with the design," he said. "Every single accident has been the result of speed."

During the bridge's recent unexpected closure, Caltrans installed reflectors and raised bumps between lanes on the S-curve so that drivers can feel the bumps when they begin to veer out of their lanes, Caltrans spokesman Bart Ney said.

Caltrans also laid down a grit surface over a steel section of the S-curve to provide better traction, Ney added.

The agency was also planning to install additional permanent signage alerting drivers of the lower speed limit on the S-curve as well as radar signs that show drivers their speeds as they pass, Ney said.