Three Fairfax County men were arrested near a farm house in Herndon early yesterday in a raid on what one federal narcotics agent called one of the largest PCP laboratories ever seized in the Washington area.

Federal Drug Enforcement Administration agents said they seized two pounds of chemicals that could produce about $200,000 worth of PCP, two handguns and a stolen motorcycle.

Charged with manufacturing a controlled substance were George Forshee, 22, and Roger Forshee, 29, both of 3729 Rugby Rd., and Michael Collins, 24, whose address was given as the farmhouse, 12319 Bennett Rd., Herndon. All three were held in the Alexandria Jail under $25,000 bond each.

Marino H. Milano, special agent in charge of the DEA's Washington district office, said one of the suspects accidentally encountered several members of the raiding party hiding in woods as he was carrying two buckets of party chemicals near the farmhouse about 2 a.m. As the agents pursued this suspect, two others in the house fled. It took about three hours to capture all three, Milano said.

PCP (phencyclidine) is an animal tranquilizer that, when used by humands, can cause hallucinations, catatonic rigidity, lack of coordination and numbness.