Nineteen primary school pupils and a teacher were attacked by a swarm of bees while hiking in Sai Kung West Country Park yesterday. About 100 students and teachers from Kam Tsin Village Ho Tung School in Sheung Shui had a barbeque at Pak Tam Chung, after which about 30 students and teachers went for a walk. As the party walked along a family trail, hundreds of bees flew out of their hive and started stinging them. A teacher alerted police by mobile phone. Police said it was not known what sparked the attack. 'We screamed for help and ran down the hill to escape. We did not look back and we kept running for about 10 minutes to the barbecue site in Pak Tam Chung,' one of the injured schoolboys said at Tseung Kwan O Hospital. The boy, who was stung several times on his arms, said no one had kicked the tree where the hive was and could not say why the bees attacked them. Twenty members of the group, 14 boys and five girls aged between six and 14, and a woman teacher, 53, were stung on their arms and legs, but the others in the group escaped injury. The victims were taken to Tseung Kwan O Hospital and Prince of Wales Hospital, where they were discharged after treatment. Officers from the Agriculture, Fisheries and Conservation Department and Food and Environmental Hygiene Department were called to the park to investigate the attack and later removed the beehive.