Reports of gunfire in a volatile north Belfast district where a bitterly disputed loyalist march took place were tonight being probed by police.
Tensions in the Ardoyne remained high despite the controversial Apprentice Boys parade passing off without major incident.
A massive security operation had kept hundreds of Protestants and Catholics apart as a small group of the loyalist order walked through en route to the main demonstration in Derry.
Four people were arrested during minor confrontations at that parade.
Earlier, a teenage Catholic boy had been battered by a mob of youths in the city in what police called a vicious sectarian attack.
But with most fears centred on north Belfast, there was relative calm as just a few taunts and a bottle were hurled at the marchers.
After the crowds dispersed, however, nationalists living along the Alliance Avenue peaceline alleged they had come under attack from loyalists in the neighbouring Glenbryn district.
Sinn Fein councillor Margaret McClenaghan said: “There have been petrol bombs, bursts of gunfire, a blast bomb and another burst of gunfire.”
The allegations came after the Ligoniel branch of the Apprentice Boys took part in the feeder procession before boarding a bus for Derry.
Sinn Fein and Ardoyne Catholics had bitterly opposed any march through the area following a history of violent clashes.
But the ruling Parades Commission upheld its original decision to allow the loyalists to walk.
Although accompanied by a band bearing the Ulster Volunteer Force insignia on its bass drum, no music was allowed to be played as the Apprentice Boys passed through.
Dozens of army and police jeeps lined the route in a bid to keep the factions apart on either side of the disputed road.
But within minutes the loyalist marchers were out of the area and on their way to Derry.
At the main demonstration thousands of Apprentice Boys joined up for the annual Relief of Derry commemoration of a 17th century defence of the city’s gates.
Although mainly peaceful, three men and a youth were arrested after scuffles broke out in Shipquay Street.
Taunts had been exchanged between marchers and nationalists in the area.
Police blamed both sides for provoking the trouble.
Earlier, sectarian tensions resulted in up to nine boys and girls pouncing on a 15-year-old Catholic boy wearing a Republic of Ireland football shirt at Church Brae in the city.
He was struck in the face with a bottle before being kicked and stamped on the head by the gang.
Inspector Bob Torrins said: “It was a brutal assault. He was very badly cut to the head, (and has a) badly bruised eye and a suspected fractured head.”