Violence flared in Portadown last night after rival crowds clashed on the Garvaghy Road.
Trouble began shortly after 7.30 p.m. when groups of nationalists and loyalists confronted one another close to Park Road, a small Protestant enclave at the lower end of the Garvaghy Road.
At first the trouble was confined to verbal abuse. But at around 8 p.m. several cars were damaged as stones and other missiles were thrown.
The loyalist crowd then came under attack from a group of some 30 or 40 nationalists, who ran towards them. The loyalists counter-charged the nationalists, who retreated to their original position.
Some 20 minutes later police arrived and managed to create a 50-yard buffer zone between the rival groups, which by this time had increased in number.
Lengthy discussions between the RUC and local elected representatives failed to defuse the situation and by 10 p.m. further units of the security forces were deployed.
The spokesman for the Garvaghy Road Residents Coalition, Mr Breandan Mac Cionnaith, blamed loyalists for the trouble, saying that masked loyalists armed with iron bars had forced several Catholic families out of their homes in Victoria Terrace.
He added that loyalists had attacked motorists driving along the Garvaghy Road.
This claim was rejected by a representative of the Park Road Residents Association, who accused Mr Mac Cionnaith of deliberately orchestrating the violence so that nationalists could film alleged RUC and loyalist violence against them.
A DUP assembly member, Mr Paul Berry, also accused the nationalists of deliberately instigating the trouble. Both groups, however, were united condemning the time it took the RUC to respond.
Elsewhere, a man was taken to hospital with gunshot wounds after some men forced their way into a house on the Carrowshea estate in Lisnaskea, Co Fermanagh, last night and fired shots. The incident occurred at 8.30 p.m.
About 50 members of the Sperrin Branch of the Ulster Unionist Party had to leave a meeting in the Orange Hall in Tubbermore, Co Derry, following a telephoned warning that there was a bomb in the building.
Police sealed off the village while a search was carried out, but no bomb had been found by late last night.