The RUC were attacked by stone throwers as they attended the scene of a fire in Belfast last night.
An RUC spokesman said two mobile classrooms in Corpus Christi Chapel on Westrock Drive were badly damaged in the fire, which was reported just before 8 p.m.
Two police vehicles were damaged during the violence.
Elsewhere, the RUC is treating as malicious a fire in Ballymoney, Co Antrim, last night that caused serious damage to a motor accessories shop and a solicitors' office on Seymour Street.
Two youths are being questioned about the fire, which was reported about 9 p.m.
Insp Alan Barton praised fire services who had to deal with what he described as a serious situation trying to put out a fire in a building that had paint, paint thinners, aerosols and other highly flammable materials inside.