The authorities had no idea how to control the panic as pupils shouted that Hutu militias, responsible for the murder of 800,000 Tutsis and moderate Hutus, had returned to finish the genocide. Eventually, the police were called and either beat children into submission or took them to hospital.
According to Jane Abatoni, co-ordinator of the newly formed Rwandan Association of Counsellors, the incident, in October, was a classic example of post- traumatic stress syndrome, a phenomenon only now beginning to sweep Rwanda. Ms Abatoni says a series of hysterical outbursts are being reported from schools across the country. "Now that life is beginning to settle down, people are beginning to realise what they have lost."
Beatrice Mukansinga, of the Barakabaho Foundation, for female genocide survivors, agrees. Even the few who did get psychological help in 1994 are returning for more. "People are even more traumatised than before."
Since the slaughter, Rwanda has been in perpetual turmoil. After the killing of 800,000 people, more than a million Hutus fled the country, led by the militiamen who orchestrated the mass murder. It was the end of 1996 before they returned from refugee camps in Congo. By then, the genocide victims had been largely replaced by a tidal wave of Tutsi exiles from earlier massacres. A precarious exercise in reconciliation and nation- building is now under way.
Only in the past year has "normality" returned. The government, now Tutsi-led, has finally flushed out Hutu extremists who were still operating in the north- west and although the killers have not been defeated, only driven from the door, people feel more secure. The downside has been a rise in psychological disturbance.
Rwanda, one of the world's poorest countries, is ill-equipped to cope. It has just 39 newly trained therapists to cover a population of 7.6 million. None specialises in children's mental health but, with the need so great, all help as best they can.
Most of Ms Abatoni's child clients are girls - boys are taught to hold emotion in - who were 10 or 11 in 1994. Most are abnormally withdrawn and say nothing about what is universally referred to as "before".
So it was with Katherine after the genocide in which her entire family, except an aunt, was killed. At Barakabaho, where counsellor Beatrice Karengera treats children and young adults (children in 1994), even now Katherine cannot speak of the 100 days of killing when she was just 14.
The miracle is that she can talk at all. Three years after the slaughter, she and a friend became convinced they had been poisoned and lost their voices on the same day. It was almost a year before she was brought to the foundation for help. "They had taken my friend to be operated on in hospital and she died," she says. "I thought they would operate on me, too, and I was afraid to die."
Only weeks after treatment began, Katherine started talking. Like most of Ms Karengera's patients, she was encouraged first to draw what she could not say. Ms Karengera has a pile of young survivors' drawings in which men lie with blood (red pen) pouring from their neck, their severed heads beside them and road blocks are manned by drunken Hutus, armed with outsized machetes.
A year after she began to talk, Katherine, now studying for university, explains that she was consumed with anger and, with everyone dead, had no one to talk to. "I lost everybody," she said. "Many people are alone and feel that nobody cares ... they turn inward with their thoughts."
Vincent O'Reilly, of the Refugee Trust (Ireland), War Child's partner in Rwanda, says there is growing awareness of the huge psychological damage to children. The trust this month opened Rwanda's first high school for girls. Counselling services will be provided on site. With more funds, more could be provided.
Mr O'Reilly hopes to promote more openness among pupils, both Hutu and Tutsi. For he believes what is unspoken is dragging them down. War Child and the Refugee Trust agree with Ms Mukansinga that only the surface of children's trauma is being scratched.
Ms Mukansinga was abroad during the genocide but arrived in Rwanda as it was ending. Eighty-seven members of her family were killed, including her parents and five brothers. She remembers bodies piled in the streets, being eaten by dogs and birds. "It will be generations before this washes through," she said. "I don't know how children, in particular, have managed even to live after all they have been through."
THE RWANDA FILE
n At the height of the genocide in 1994, an estimated 10,000 people were being shot, burnt or hacked to death every day. Within 100 days, 800,000 were dead.
n Children were deliberately exploited by the militia to pick out Tutsis and were forced to take part in the slaughter.
n By 1997, 2,000 children had been detained on suspicion of committing acts of genocide.
Amnesty International: www.amnesty.org.uk