Police in Northern Ireland are on high alert following sectarian riots Wednesday in North Belfast. At least 14 policemen and six civilians were injured in the clashes.

The clean up has gotten under way in North Belfast after some of the worst rioting in months between Roman Catholics and Protestants.

The violence began after a shoving match outside a Catholic girl's school on Wednesday afternoon, and it continued into the early morning hours Thursday.

Police said as many as 500 Catholic and Protestant protesters fought running street battles with each other. They also attacked policemen with scores of gasoline bombs, bricks and fireworks and burned several vehicles.

The Catholic Holy Cross primary school, where the trouble began, was closed Thursday because administrators feared for the safety of students.

The school was the focal point of protests for several months last year. Protestants held daily demonstrations against Catholic parents passing through a Protestant enclave to bring their children to the school.

The conflict highlights the territorial disputes that continue to fester in Northern Ireland despite a 1998 peace agreement to end 30 years of fighting between Irish nationalists, who are mostly Catholic, and pro-British unionists, who are predominately Protestant.

The chief administrator of the Holy Cross school, the Reverend Aidan Troy, said he cannot rule out closing the school, but he does not want to.

"I hope that we will be able to recover, as terrible as yesterday afternoon and last night was, but I've got to have that hope, and I do have that hope that we can recover," he said.

A Protestant community leader, Presbyterian Reverend Norman Hamilton, said dialogue is needed to defuse tensions.

"We need to have a local inter-community forum with the civic representatives and the politicians so we can deal with the daily incidents that flare up into the sort of conflagration that we had yesterday," he said.

In the meantime, about 400 policemen and soldiers are on patrol to guard against another outbreak of violence.