Six cars were set on fire as a mob went on the rampage in Co Down overnight.
Police were also pelted with stones by up to 50 people who had gathered on the Bowtown estate in Newtownards.
A petrol bomb was thrown into the neighbouring Whitehorn area as well, although no damage was caused.
Tensions have been running high in Bowtown, a loyalist stronghold, since police raided a drinking den on Friday, seizing a gambling machine and alcohol. When trouble broke out last night extra police were drafted in.
Iris Robinson, the Democratic Unionist MP for the area, said today: "While no one is attempting to deny the existence of paramilitary problems in the town, Sunday night's events represent a watershed.
"Never (in my time) as an elected representative for this area have the police been attacked in such an orchestrated and sustained manner in relation to an issue which is purely criminal."
"It would appear the disgraceful behaviour at the Bowtown estate may be linked to a successful operation by the local police in closing down an illegal drinking den in the estate and would therefore seem to have been orchestrated, in order to lure police into the estate for payback.
"This unacceptable behaviour has obviously been organised by those who have no respect for the maintenance of law and order, she said."
PA