Northern Ireland officials say rioting erupted early Wednesday on the streets of west Belfast, before the start of a major Protestant march.

Police say they fired plastic bullets at the nearly 200 rioters who responded by throwing rocks, bricks and gasoline bombs. Police said at least seven officers were injured. No civilian injuries were reported.

The riot in heavily Catholic west Belfast came at the start of the divisive annual holiday known as “The Twelfth,” marking the Protestant victory in the Battle of Boyne in 1690. Tens of thousands of Protestants march in Northern Ireland each year to commemorate King William's victory over the Catholic King James, rival claimants of the English, Scottish and Irish thrones

Earlier this month six Northern Ireland police officers were injured in similar rioting in Belfast following a Protestant march.

Protestant loyalists in Northern Ireland want to remain part of the United Kingdom, while Catholic Republicans want to break free of British rule and join the Irish Republic. The 1998 “Good Friday” peace accords have largely ended a 30 year cycle of sectarian bombings and shootings in the province and led to the creation of a power-sharing Northern Irish Assembly.