Two fires over the weekend extensively damaged the wooden grandstands and two buildings at Freestate Raceway in Laurel, Howard County fire officials reported yesterday.

The state Fire Marshal's Office said both fires, one on Saturday that nearly destroyed the grandstand building and another early yesterday that gutted the former jockey clubhouse, were deliberately set.

Investigators are searching for two youths, reportedly between 12 and 15 years old, who were seen running from the property Saturday, Fire Marshal Bob Thomas said. "At this point we don't have any clear-cut suspects in connection with the second fire," he said.

The former track at Route 1 and Gorman Road, originally called Laurel Raceway, was the state's first harness racing track. In its final year of operation it was leased by developer Mark Vogel from a partnership controlled by late racing magnate Frank J. DeFrancis.

Vogel moved the track's racing dates to his Rosecroft Raceway a year ago and Freestate was closed, ending decades of racing.

The 107-acre property, considered prime real estate because of its location between Washington and Baltimore and close to several major highways, was sold to the Cafritz Group, headed by Conrad Cafritz, for conversion into an industrial park and office complex.

It has stood vacant ever since, suffering occasional vandalism, neighbors said.

Demolition of the stands and more than 25 raceway buildings was to begin in the next four to six weeks, Thomas said.

Heavy smoke from the first fire was discovered by a passerby around noon Saturday. It took firefighters from Howard and Prince George's counties about an hour to bring the blaze under control, local fire officials said.

Much of the grandstand and part of the grandstand building collapsed.

"Any time you have vacant property . . . that is not totally secured against trespass, it does present a target for arson," Thomas said. "We were not surprised by this."

He said evidence of arson was found at the grandstand, but declined to describe it. "It didn't take a genius to figure out how to start the fire," he said

There was "no advantage" for a developer about to raze the property, Thomas said, "because there is still a lot of cleanup involved . . . . Buildings to a degree are still standing."

Two principal figures involved in the the raceway property have faced other difficulties in past months.

Vogel, a Prince George's developer, was arrested Sept. 13 on a charge of possession of four grams of cocaine. The State Racing Commission has ordered an examination of finances related to Rosecroft Raceway and Delmarva Downs after learning that Vogel may have pledged track assets to troubled real estate ventures.

Cafritz, a Washington-based real estate investor, has been fighting to stay out of bankruptcy and owes a total of $1.1 billion to about 70 lenders. He has fallen behind on interest payments and has asked creditors to give him until at least the end of 1993 to sell or refinance his holdings.