AMHERST, MASS., FEB. 18 -- As people watched in horror, a man drenched his body with paint thinner, set himself on fire and burned to death yesterday afternoon in apparent protest of the U.S. involvement in Persian Gulf War.

Witnesses told police that the man, believed to be in his 20s, set down a sign saying "peace" before dousing himself with two gallons of the flammable liquid. He ignited it with the second of two matches he lit, producing what one police officer called "a fireball" on the common in front of the town hall shortly before 2 p.m.

The man's identity was not released by Amherst police, who said an autopsy will be performed in Springfield Tuesday morning.

"I heard this woman saying somebody is pouring gas all over himself," said Kenneth Albrecht of Belchertown, who was waiting for a bus. "I turned around, and the guy was engulfed in flames. I didn't know what to do. He was screaming."

"It was over in a matter of seconds," said one woman, who asked not to be identified. "He was spewing a big cloud of black smoke."

"I've never seen anything like this," said Amherst Police Chief Donald N. Maia, who has been chief for 18 years in the college town, which has been a center of war protest.

" It was really horrible," said Pat Lattuca, a waiter working nearby who rushed to the scene.

"The man lit a match which went out, then lit another which resulted in a fireball which engulfed him in flames," said Charles Flahive, another Amherst police officer.

Several people used their coats to try to put out the fire. Police Officer Christopher Pronovost arrived quickly and put out the flames with a fire extinguisher from his cruiser.

It was over in perhaps two minutes.

The death occurred about 1:50 p.m. on the Amherst common, the scene of weekly protests against the U.S.-led war against Iraq, but there was no organized demonstration at the time.

The man had placed a small cardboard sign with the word "peace" written on it and attached a Massachusetts driver's license, according to police and witnesses.

Maia said the man was not believed to be a student at any of the schools in or near Amherst, which include Amherst College, the University of Massachusetts and Hampshire College.

The self-immolation was evocative of the Buddhist monks' burnings in Saigon to protest the Vietnam War.