Two RUC officers were injured after an attack by a crowd of up to 200 people in Derry last night.
The mob used bottles, coins, beer cans, glasses, and bricks for one hour, an RUC spokesman said. Ambulance personnel also came under attack, he added.
The RUC used batons to hold back the crowd as officers tried to rescue an injured man who had fallen into an enclosed area in the Strand Road area.
Four people were arrested for public order offences.