When inspectors visited the Peckham Academy earlier this year they praised the new inner-city school for providing a "a safe haven for its pupils".
So it has been frustrating for teachers to hear the academy linked to a gang-war in South London and a rumoured threat of a drive-by shooting.
Police asked the school and the Harris Academy for Girls in nearby East Dulwich to send pupils home early a fortnight ago today after receiving reports of a planned gun attack.
Since then police have been reassuring parents and the community that there is no evidence that pupils at either of the schools are linked to the gangs. But it has been too late to stop the bad publicity.
Peter Crook, principal of the Peckham Academy, said that he and pupils had been angered by recent press reports linking young people in Peckham to gang violence, as many of the events had occurred in other boroughs and involved adults.
"It's going to make for an interesting media studies lesson," he said. "I was in class the other day and pupils were asking 'Why is this happening to us?' They are getting on with their education. They only worry if the adults worry and we are not going to hype this up."
The school closures followed a turf war between the Peckham Boys, a gang which has existed for around 10 years, and the Ghetto Boys, based in Lewisham. A gang dispute last month at a party is believed to have led the Peckham Boys to fatally stab a 29-year-old, who was unrelated to the groups.
Superintendent David Chinchen of Southwark police said there had been intelligence from a number of sources suggesting areas around the schools would be targeted. "It wasn't directed at any person or at the schools - it was just the locality and the time," he said.
Mr Chinchen said the police were now considering how to improve dealing with similar situations, including keeping pupils on the school sites and getting information to parents faster.
He said that specially-assigned school beat officers had helped maintain good communication with teachers and had kept a watch on pupils as they walked home.
The number of young people involved in the gangs was very small, in the 10s, he stressed. "As soon as you start talking about the gangs you run the risk of making them look trendy and attractive to young people," he said.
"The reality is that it is rare for young people of school-age to be involved and any violence by the gangs tends to be targeted at each other."
Although it is unusual for under-15s to be in gangs, some join junior off-shoots such as the Young Peckham Boys, whose members fatally stabbed 10-year-old local schoolboy Damilola Taylor in 2000.
Mr Crook said: "It was terrible that Damilola Taylor was murdered, but that was six years ago. It isn't a live issue for our children, just the media."
One person who meets regularly with teen gang members is Camila Batmanghelidjh, founder and director of Kids Company, which runs projects supporting vulnerable young people in south London.
She worked with a current leader of the Peckham Boys 10 years ago when he was 14, as well as a leader of another notorious group, the PDC (Poverty Driven Children).
"The structure of the gangs has not changed much," Ms Batmanghelidjh said.
"What has changed is it is now much easier for them to get a gun for pound;30 - the kind of gun that lets them spray a room with bullets."
She said thousands of young people in south London, some as young as nine, had low-level involvement in the gangs as occasional minions, often because they had been bullied into it. But she agreed that the number of serious gang members was small.
Ms Batmanghelidjh said it was important to treat the teenagers as individuals, rather than members of the group, particularly senior members who often had extreme psychological problems.
"They have carried out the most horrendous things, and they are so morally and emotionally exhausted that they do not care if they live or die," she said. "But these are boys, and if you give them a chance to talk on their own, they cry."