BELFAST, Northern Ireland — Northern Ireland police say 20 officers have been wounded in overnight Belfast riots that followed a token Protestant parade past a militant Catholic area, an annual confrontation that has triggered street fights for four straight years.

The commander of the police operation to quell rioting in the Ardoyne district, Assistant Chief Constable Will Kerr, says Irish Republican Army die-hards fired about 10 gunshots at his officers early Friday but none was hit.

He says 20 officers have been treated for cuts, bruises and burns suffered during 10 hours of rioting that started after two dozen Protestant members of the Orange Order brotherhood marched past the edge of Ardoyne, a power base for IRA factions.

Most violence happened after authorities permitted Ardoyne residents to mount their own parade two hours later.

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  • A member of the Orange Order North Belfast, seen before a parade in Northen Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • A Protestant bandsman joins the parade North Belfast, Northen Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • A member of the Orange Order parades from North Belfast, Northen Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • Protestant bandsmen prepare to parade in North Belfast, Northen Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • Nationalist residents shout at police as a Orange Order parade passes the Ardyone area of North Belfast, Northen Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • A Protestant bandsman drinks beer before marching in North Belfast, Northen Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • Orange Order members march past the mainly Catholic Ardyone area of North Belfast, Northen Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • A man pours petrol on wood as he lights a massive bonfire in the Shankill Estate, West Belfast, Northern Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • Protestants throw an Irish flag onto a massive bonfire in the Shankill Estate, West Belfast, Northern Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • Houses are boarded up to stop them catching fire as people watch a massive bonfire in the Shankill Estate, West Belfast, Northern Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • Protestants watch a massive bonfire in the Shankill Estate, West Belfast, Northern Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • Protestants watch a massive bonfire in the Shankill Estate, West Belfast, Northern Ireland, Thursday, July 12, 2012. (AP Photo/Peter Morrison)

  • Children stand on a massive bonfire in the Shankill Estate in West Belfast, Northern Ireland, Tuesday, July 10, 2012. (AP Photo/Peter Morrison)