Rioting flared in parts of north Belfast between rival supporters of two Glasgow teams after Rangers clinched the Scottish Premier League from Old Firm rivals Celtic.
About 200 people clashed in the Ardoyne area about 4pm yesterday evening after Rangers won the league when Celtic were defeated in the final minutes by Motherwell.
There were also disturbances arising from the result in the Limestone Road and Whitewell areas and reports of tensions in west Belfast. The security gates at Lanark Way that separate the nationalist Falls from the loyalist Shankill were locked shortly after Rangers won.
The PSNI said 18 of its officers were injured when they intervened to try to quell the trouble at Ardoyne shops. One woman officer was partially dragged from a police vehicle and had a bottle smashed over her head, police reported. Police said they were attacked with sticks and bottles. They used two water cannon to try and disperse the rioters.
The PSNI said four of the officers were treated for injuries in hospital. The police, clad in riot gear, were attacked when they arrived at Ardoyne to separate the rival factions. Throughout yesterday evening motorists were warned to avoid Twaddell Avenue, Woodvale Road and Crumlin Road at Ardoyne shop fronts because of the rioting.
"Police who intervened to separate rival groups came under sustained attack," said Supt Gary White, operations manager for north Belfast. He said police would use CCTV footage of the rioting to prosecute those involved.
The situation remained calm but tense last night as police and community representatives monitored the situation.