Five PSNI officers were injured as they tried to break up a street brawl outside a pub in Co Fermanagh.
An ambulance crew was also stopped from reaching a wounded man when a mob of up to 30 people clashed in Enniskillen.
The crowd turned on half a dozen officers when they arrived at the early morning fighting in High Street. Four policemen and one policewoman sustained face, back and neck injuries, the PSNI said.
As the trouble flared, an ambulance was called in to treat an injured civilian. But the crew was forced withdraw when they were verbally abused. The wounded man was later taken to hospital by local people.
Two men were arrested for riotous behaviour and assault on police.
Enniskillen Police Chief Inspector John Maxwell described it as a despicable attack on members of the emergency services.
PA