The death of a Kent teenager underlines how tragic incidents can hit the nicest neighbourhoods - and rock the whole community
On Wednesday morning a sixth form walked down a hill from school to St Mary the Virgin in Hayes, Kent, for the funeral of a 16-year-old girl called Emily Sims. About 100 young people in dark uniforms hugged each other as they recalled their dead friend. Even some brutish-looking boys sobbed.

Half-way through the service a girl called Lucy Bodycombe walked to the lectern and began to speak: "I know some of us have taken her death badly, and it is hard to accept, but Emily wasn't the type of person who stayed down for long and I know she wouldn't want us to be that way ... Emily loved parties and, although it is hard to say, she died doing something she loved, which many of us in this world unfortunately will not. I spoke to her at the party and she seemed as happy as always. Although I didn't see her after the accident, those of you who did, or know of anyone who did, please remember her by her smile, by that loud and loving personality she had." When Lucy sat down, a tape played "American Pie" by Don McLean.

Most of the young people hearing this had been at the party where Emily Sims was killed four weeks ago; many of them had seen her crushed under a van as the evening dissolved. She died just outside the party venue as two other partygoers were driving off after a fight.

Tragedies like these are not really big news any more, and the media interest is predominantly local. For this is not an incident that speaks of an unruly town, nor of unbridled lawlessness. But it is an event that has already scarred a school and a small community, and may never be forgotten by those touched by it. At the root of this story lies a horrible fact: that a young girl can go out one night to a dance and never return home.

This incident and its causes are particular, specific; but the incomprehension and fear such an incident arouses is far-reaching. A young man had hired the pavilion of Bromley Football Club for his 17th birthday, had sold tickets to his friends and their friends, and on the night a huge crowd showed up. Later, most would say they were having a great time, up until about midnight. There were gatecrashers, and people drank under age - the usual teenage Friday night stuff. But there were also some weapons, and a fight, and then a terrible incident in the car park that resulted in a death so gruesome that those who saw the body required professional counselling.

Two local lads aged 15 and 18 have been charged with murder and attempted murder. The subject of the attempted murder, another sixth-former who was knocked to the ground by the same van that crushed Emily Sims, attended the funeral on crutches.

At Bromley and Orpington police station, Detective Inspector Roger Somerville has seen this sort of thing before, and, as before, he's told the press that 95 per cent of the young people round there are just fine, regular kids.

In the past month he and his colleagues have interviewed about 300 of them. Their statements are stacked up in the cramped incident room that once was a dairy. A man is highlighting passages with a yellow pen; a woman is cross-referencing on to a huge circular file. "We still favour a non-computerised method for these types of incident," DI Somerville says.

These types of incident: you cannot miss the weariness in his voice, and a certain stoicism. Policing of public parties should be looked at, he says, "but how can we possibly put people in at every event?" It is clear he wants to talk about the details of the case - such is his anger at what he believes occurred - but his comments are constrained by the laws of sub judice.

DI Somerville was woken with the news of Emily Sims' death at 3am on the Saturday, and he accompanied her parents to the mortuary the following day. Between these two events he talked to the first witnesses, the people who walked into the police station before the official appeal for help. Among these were the two youths who were later charged with murder, accompanied by their parents and solicitors.

"Most of the witnesses described very similar incidents," DI Somerville says, "and the trauma they were experiencing was immense." He regrets that this will continue for some time, but this is the familiar process: soon there will probably be applications for bail, which will incite local anger; the parents of the older youth may have their van restored to them, the van involved in Emily's death, which will then be seen locally; in a few weeks there will probably be committal proceedings, at which witnesses may be called to relive it all. And then there may be a trial.

Before that, DI Somerville and his team will be revisiting the school to take follow-up statements. For people who have had no contact with death, this was a cruel introduction. "Counselling can help, but when you saw what happened, and are constantly asked to repeat it, you just can't take that grief away. Most of these youngsters have never seen death before."

Police found it easier to talk to the witnesses at school, in the presence of a teacher, rather than at home, in the presence of a parent. "When you're taking a statement in a person's living room you may have a parent sitting there, and if you're asking a youngster for their story, you may get a parent butting in, saying, `I didn't know you went there with so and so' or, `I didn't say you could have a drink or a smoke'. At school the truth comes out."

There are almost 1,200 pupils at Hayes School, a traditional grant-maintained institution with a high level of academic achievement. One hour after Emily Sims's funeral, John Catmull, the head for the past five years, is back in his office considering the lessons that might be learnt from her death, and how best to reassure his students. He talks of abandoning timetables for communal grieving, of how her friends held an assembly in her honour.

"This is one of the most shocking and horrifying experiences I've had," he says. "But compared with the emotional turmoil my students have undergone, and that of the Sims family itself, my experience pales into insignificance."

When the parents of prospective pupils come to see him, Mr Catmull tells them he regards his school as an outsize family. It is clear he shares their concerns. "Parties like that are very common, there is very little for young people to do these days; they can hang around, go bowling ...." And then a phrase from another age: "And some of the uniformed organisations are not as popular today as they once were."

So what can be learnt from what happened? "That is very difficult, because it involves a lot of speculation. One would have to look at supervision, access to the premises, the parking, the lighting ... but even then I wouldn't know where to begin."

Mr Catmull read a brief passage at Emily's funeral, and hung his head when others spoke of her A-levels, of her time with the girl guides, and of how she was "thinking of someone very special to her" on her last evening.

"One of the sad things about modern headship in a large school is that I have very little time to spend with individual students," he said later. "It would be wrong to pretend I knew Emily well. I tend to know the naughty youngsters rather better than the majority of students, and Emily wasn't one of those. I knew Emily mostly by her smile. The descriptions of her at the funeral were very accurate; that is what will be missed. She was so visible because of her ebullient personality.

"For her life to be snatched like that is wholly unsatisfactory. It's hard to describe the mood, but the sadness and the air of disbelief and disquiet just pervaded the atmosphere of the whole school for a week after her death, and it returned a little bit today."