For Halloween, 60 friends of 19-year-old Eric Valainis gathered at his Rockville home, which was decorated with spider webs and pumpkins.

Many wore festive costumes, including Valainis' mother Lidia, who was dressed as an animal tamer, with top hat and bullwhip.

But the party suddenly turned sour, swelling into a rampage of 300 people on the street of modest red-brick houses. The brawl finally was quieted by 40 police officers from Montgomery County and Rockville.

"It was unbelievable . . . to see 300 people bent on destruction and hurting each other . . . with sticks, clubs, shovels, feet and fists," said Sgt. Paul D. Catherwood of the Montgomery County Police Department. "To see 300 people take to the streets, stabbing people, assaulting police -- just no boundaries. I've been on the street for 13 years, and this is the worst violence I've ever seen."

Before the evening ended one man was stabbed and two were run over by a pickup truck, police said. Randall Paul Earp, 21, of Gaithersburg was charged with assault with intent to murder in the stabbing of Michael Lawrence, 22, of Wheaton. Lawrence was treated at Suburban Hospital and released, police said.

Charges were pending against a 17-year-old accused of driving the pickup truck that police said was deliberately run over Larry Eugene King and Gary Lee Wilt, both of Rockville. Both were treated at Suburban Hospital and released.

Thirteen other men were arrested and charged with disorderly conduct, resisting arrest and drinking in public, police said.Lidia Valainis said yesterday that the evening's events were a "nightmare."

"I saw some people coming down the street with sticks and clubs," she said. "Then a pickup truck came down the street and hit two people. Someone beat my 15-year-old with a shovel, over the head. When Michael Lawrence tried to help my son, he got stabbed. Then I went and tried to take the shovel from the guy.

"It was insane."

"We were having a nice costume party until this happened," she said, explaining that she had decorated her home with spider webs and pumpkins, and served lemon-and-lime drinks. A four-piece band, Fatal Sin, provided music for the party.

Exactly what triggered the violence wasn't clear yesterday.

Valainis blamed the trouble on a group of older youths armed with sticks and shovels who appeared on Randolph Road, a busy four-lane thoroughfare.

Catherwood said the violence was sparked by an altercation that began at the Valainis party when John Baxley, 17, of 11444 Schuylkill Rd., drove to the party in a brown pickup truck to pick up a girl friend. Baxley then left the party and ran to a nearby pay telephone and called his mother, asking her to come and get him because he was being pursued by several youths, Catherwood said.

"The mother responded by loading up a second pickup truck with family members and driving to the scene," Catherwood said.

The beds of the pickup trucks contained a variety of sticks and tools, including a shovel and an ax handle, which Baxley's stepfather, Doug Alexander, uses in his work, Catherwood said.

Catherwood said that when the second Alexander truck arrived in the 4900 block of Randolph Road, the youths on the street rushed to it and seized the sticks and tools and used them to attack the truck and try to get at the occupants inside the truck.

"It was unbelievable," Catherwood said, adding that the use of drugs and alcohol had contributed to the melee.

Most of the people involved in the fight were from the Rockville and Wheaton areas, according to Catherwood, although it was unclear why they all gathered at the party. The police said that some were trying to crash the party.

"When that many get together, it's like a keg ready to go off," Catherwood said. "More drugs, more alcohol make it worse . . . . It's violence gone rampant."

At some point in the confrontation, John Baxley, who had returned to his truck, left it in an effort to flee the youths who had surrounded the truck, according to his mother, Patricia Alexander. She said that her husband then got out of their black pickup truck to assist John.

"Some big, older guys came and beat him down to the ground," she said. "I got out of the truck and got a stick from the back of the truck and cracked a couple of heads to get them off my husband.