A deer joined the morning commute into San Francisco on Tuesday, bounding onto the Golden Gate Bridge and loping across the entire span as bridge officials and motorists watched in amazement.

It was the first time anybody can remember that a deer, or any other animal, for that matter, has made it from one side of the famous bridge to the other in one piece.

It took the deer less than 10 minutes to commute from Marin County to San Francisco, where the animal zipped through the FasTrak lane at the toll plaza, took the 19th Avenue exit and then disappeared into the Presidio.

"When I first saw the deer, I thought, 'Maybe it's a dog' -- then I said, 'Oh my gosh, that really is a deer,' " said Amorette Ko, the executive assistant to the general manager for the Golden Gate Bridge, Highway and Transportation District, which has offices at the toll plaza.

Ko grabbed her camera and snapped three pictures as the deer ran by.

"That deer was really galloping," she said. "It's so amazing. We've had lawn mowers go across the bridge, but never a deer."

Traffic in the four southbound lanes and two northbound lanes was quickly brought to a halt by the California Highway Patrol. The frightened deer, followed by a lane diversion truck and a patrol car, galloped across the span in the southbound lanes.