It is not often that a pack of violent teenagers looking to pilfer candy and chips from stores overruns the streets of a well-heeled neighborhood. But that was the case in SoHo last week, when police said more than 30 high school boys from the Chelsea Vocational High School let loose on Thompson Street. The result was three arrests, a broken nose, and several fearful shopkeepers.

It began with a scene that has been repeated a handful of times since Hasan Ahmed came to New York from Bangladesh two months ago. Several students playing hooky from the high school at 131 Sixth Ave. began harassing him, knocking gum and candy off the shelves of his cramped convenience store and slipping them into their pockets.

The crowd of students, who were beginning their final week of classes before summer vacation, grew to “well over 30 youths,” a police officer who was at the scene, and who wished to remain anonymous, said.

“The students went 12 deep and took over the entire street,” an employee of a shoe store said. The employee, who requested anonymity, estimated there were up to 50 students milling around on Thompson Street.

“There was a huge pool of people. It was so frightening,” she said.

According to Mr. Ahmed, the police did not arrive until 20 to 30 minutes after he called them.

“I called them and it took them 30 minutes, maybe 20, to get here,” he said. “This is not the first time – these students have bothered me, stealing soda, ice cream, and candy five times already.”

According to Mr. Ahmed, an employee at a coffee shop across the street, Porto Rico Importing, entered the store and began defending him against the teenagers, who had become agitated and violent when Mr. Ahmed called the police. An employee at the tiny Greek restaurant Snack also came to his aid.

The coffee-shop employee was punched in the nose and sent to St. Vincent’s Hospital, where a student with broken ribs was also treated. Witnesses said the Snack employee was beaten and suffered minor injuries, but he did not return calls seeking comment.

The Porto Rico Importing employee did not want to be identified and declined to comment on his experience.

“It was a rampage, and it is all the more unbelievable in a neighborhood that has the one of the highest rents per square foot in the city,” the director of the neighborhood civic group SoHo Alliance, Sean Sweeney, said. He said the police had confirmed the arrest Monday of three students. The Police Department did not comment yesterday.

Mr. Sweeney, who called Chelsea Vocational “one of the worst schools in the city,” said students stole rakes and shovels from the back of a truck from the city’s Department of Parks and Recreation and used them to intimidate residents and shopkeepers.

The students also jumped from hood to hood along the parked cars that line Thompson Street to escape from the police, witnesses said.

“When the cops showed up, I couldn’t believe how quickly they dispersed,” the employee of the shoe store said.

The school had a strikingly high number of suspensions and of students who have been involved in major crimes compared to similar schools in the city, according to an 2003-04 annual report card issued by the city.

Chelsea Vocational had 283.3 suspensions for every 1,000 students, compared to 74.6 suspensions per 1,000 students in similar schools, according to the report. The school, which has a school accountability status of “in need of improvement,” has seen a spike in suspensions since 2002, when it registered 49.6 suspensions for every 1,000 students. In the 2003-04 school year, students were involved in one property crime, five “crimes against persons,” and eight “other crimes.” Schools of similar size – enrollment at Chelsea Vocational last year was 1,020 – had, on average, 0.4 property crimes and crimes against persons and 4.5 other crimes, the report said.

The area covered by the 1st Precinct of the NYPD, which includes SoHo, has experienced a 65% increase in burglary through May 29, compared to the same period last year, according to Police Department statistics. Robbery is down 7% and felony assaults have dropped 26%. Citywide, burglaries declined 13% in the first five months of the year, while assaults dropped 8% and robberies increased 1%, according to the police statistics.

City Council Members Alan Gerson and Christine Quinn, Democrats who represent opposite sides of Thompson Street, said they would discuss the incident and continuing violence against local shopkeepers with the principal of the school and police in late August, before the start of the next school year.