Firefighters were attacked five times across Northern Ireland on Sunday night, the Fire Brigade has said.
One officer was hit by a stone and a fire engine was damaged in the attacks in Belfast, Lurgan and Newtownards.
Fire officer Graham Crossett said attacks on crews are making their job very difficult.
"Fortunately we had only minor damage and no injuries on these occasions, but the potential is always there for serious damage," he said.
Meanwhile, it is hoped that a campaign targeting children will help cut the number of hoax 999 calls in Northern Ireland over the Easter holiday.
Emergency services stage a rescue demonstration for the children
Last year the Fire Brigade alone received over 700 hoax 999 calls over the Easter period, a 20% increase on the previous year.
The campaign aims to deter children between 9 and 14 years of age who are the key group for making hoax calls.
All the emergency services are taking part in the initiative.
The campaign was launched at the Fire Brigade's Belfast training centre on Monday, with more than 100 schoolchildren present.
Fire, rescue and road crash drills were carried out by fire crews, police and ambulance crews to show pupils the consequences of making a hoax call.
They were also shown control room technology, where calls can be immediately traced, even to mobile phones.