SAN MATEO (Map, News) - A group of mischievous kids may have been responsible for a fire that started at the Bay Meadows Race Track on Saturday afternoon.

Around 4:45 p.m., during the last races of the day, a fire started in a pile of boxes and computer parts at the north end of the famous track’s grandstands, San Mateo Battalion Chief Jeff Barile said.

The boxes and computer parts were being stored in an indoor patio area of the long-closed Tipster’s Café, Bay Meadows General Manager Bernie Thurman said. A canopy over the area also caught fire, and a large amount of smoke started spreading through the north end of the grandstand. There were no injuries, Barile said.

Bay Meadows security officers and fire watch were the first to respond to the blaze, and it was largely out by the time 20 San Mateo firefighters arrived, Barile said. Crowds were evacuated from that end of the grandstand, while the debris was investigated and cleaned up. Fire investigators could not find any accidental cause for the fire and suspect arson was the cause of the “suspicious” blaze.

Thurman said authorities are going through Bay Meadows’ security tapes to find the cause of the fire, but she wouldn’t comment on suspected causes.

Bay Meadows employee Gary Darasout, however, said he’d been told by the administration that security tapes showed a group of mischievous kids hanging out near the patio just before the fire started.

San Mateo police Sgt. Art Sanchez said the case is under investigation by police.

On Sunday, the debris from the fire had been cleaned up and removed, but black marks stained the floor and the wall, and ash covered the computer terminals still in the area.

The doors were all wide open to air out the grandstands, which still were tinged with a stench of smoke and ash.

Despite the suspicious fire, it was clear the incident hadn’t chased any Bay Meadows racing fans away on Sunday: Crowds lined betting terminals and sat on benches right next to the area that had caught fire.

Thurman said the crowds didn’t seem fazed even in the midst of the fire.

“At first I was worried there’d be a stampede out of there because of the fire, but the customers didn’t seem too concerned about the smoke. They were more concerned with getting their bets in,” she said.

Bay Meadows Race Track is set to shut down after Aug. 17, the last day of horse racing there.

kworth@examiner.com