VIRGINIA BEACH, Va. (AP) _ National Guardsmen with rifles helped enforce an overnight curfew after a second night of violence followed the looting of more than 100 stores by young people in town for a fraternity festival.

The curfew issued after a Labor Day weekend gathering of students from mostly black colleges turned violent was lifted this morning.

The resort's main thoroughfare, Atlantic Avenue, was reopened and families began heading for the beach for the last holiday of the summer.

Officials in this town of 250,000 praised police, but a civil rights leader said officers contributed to the tension that touched off the riot.

A 35-minute sweep by club-wielding officers late Sunday added dozens of arrests to the 160 arrests and 395 citations between Friday evening and Sunday afternoon. Police had no immediate figures on the number of arrests overnight.

Two people, both over college age, were shot in the first night of violence.

''Last year, everything was real nice. There was no violence ... but this year the place was jammed with police and they were hassling people,'' said Paul Williams, a 21-year-old student from Philadelphia's Temple University.

Another witness said some participants chanted a slogan from the hit film ''Do The Right Thing,'' which is about racial violence in New York City.

''We will not tolerate lawlessness from anybody,'' Mayor Meyera E. Obendorf said. ''Let the word go out that Virginia Beach will not stand by and watch as unruly individuals trash our city.''

In an interview on NBC's ''Today'' show this morning, the mayor said police ''have shown extraordinary restraint'' in making arrests. She said police had fired no shots and had not used tear gas.

She said the city has ''gone out of its way'' to welcome the young people gathered for the annual Greekfest, which attracts students from up and down the East Coast. She said some students had complaints about the way they were treated, but ''there's no excuse for trashing a city if you're not happy with your circumstances.''

But Jack W. Gravely, president of the Virginia chapter of the National Association for the Advancement of Colored People, faulted the city's tactics as much as ''an element who came to disrupt'' the students' gathering.

During last year's Greekfest, police cleared smaller groups of young people from the street. Other large fraternity gatherings have erupted in violence in the past, including a beach party in Wantagh, N.Y., in July at which three people were shot. And some Florida towns packed with college students every spring have seen scattered street disturbances, alcohol problems and vandalism over the years.

Sunday night, dozens of officers and 150 National Guardsmen armed with assault rifles and wooden batons left the Visitors Center for the beach area two blocks away.

''Once the police came on the scene, the tension level rose,'' Gravely said. ''The students had what I call an attitude of controlled defiance. They did not understand what they had done to warrant this treatment.''

He said Virginia Beach officials should have been better prepared for the annual gathering of students from predominantly black East Coast colleges.

City officials said they had no choice but to use force after young people went on a rampage early Sunday down beachfront Atlantic Avenue.

The authorities estimated 100,000 young people jammed a 30-block section around 2:15 a.m. When police tried to clear the streets, shots were fired, more than 100 businesses were looted and small fires were set in the streets, city officials said.

By the time order was restored around dawn, four people were reported injured. They remained in hospitals today, two with gunshot wounds, one critically injured in a balcony fall and one in serious condition after an auto accident during the disturbance.

By 6 p.m. Sunday, Atlantic Avenue was again crowded with young people, though many shops were boarded up. Two hours later, officials closed all streets leading into the beach, allowing in only residents.

A short time later, the guardsmen moved in, followed by explosions that sounded like firecrackers, causing momentary panic among about 250 young people.

Bottles were thrown at officers. Ten-man squads of police, backed by an armored state police truck and a SWAT team, began making arrests.

By 9:30 p.m., hundreds of police in wedge formations swept the beachfront, with a police helicopter overhead. They were met by a hail of bottles from balconies and parking decks, but cleared the streets by 11.

''When they tried to move people, it went crazy,'' said Errin Smith, 20, of New York. ''People were yelling 'Fight the Power 3/8' At first people were just having a good time, but they harassed us from the minute we got here.''

''Fight the power'' is the musical theme of ''Do The Right Thing,'' a current movie about racism and the death of a young black man at the hands of police.

The mayor said the decision to clear the streets was made by commanders at the scene after reports of looting and shots fired.

Gravely said he and an NAACP attorney were meeting with the mayor at the time and were not told of any looting or shooting.

''It's been like we're being singled out because we are young and black,'' said Charles Stone, 23, of New York City.

Merchants denied slighting the students, most of whom they said were nice. But some shopkeepers said they were not surprised by the trouble.

''We tried to welcome these people. We'd been hearing rumors all week that something was going to happen,'' said Bobbi Basnight, an Atlantic Avenue merchant.

''Our problem is we had so many people in a small area,'' said Arnie Cohen, whose shop was spared. ''I don't care if they were Jewish, black or whatever ... with all those people with so little to do and some of them drinking ... it's a volatile situation.''