Up to 50 petrol bombs were thrown at police officers during violence outside a Derry city polling station last night.
A PSNI spokeswoman said the rioting, during which 15 paint bombs were also hurled at police, broke out after the polling station at Creagan closed at 10.00 p.m.
Police were also attacked as they were escorting ballot boxes from polling stations in the Shantallow and the Ballymagroaty areas of the city.
There were no serious injuries reported, although a PSNI spokeswoman said one man in the crowd of rioters was set alight by a petrol bomb. She said the flames were put out and the man was dragged away before an ambulance called by the police could reach him.
A returning officer was also slightly injured by glass broken during disturbances outside another polling station in the Carnhill area.
Voters were yesterday choosing the three MEPs for Northern Ireland and hundreds of members of local and town councils.
Over a million people were eligible to vote at 612 polling stations. The turnout is through to be around the 50 per cent mark. Counting will not begin until Monday.