A fireman has been taken to hospital with a head injury following an attack in west Belfast.
Two appliances attended the fire at a derelict building
The man was struck by a brick while attending a fire at a derelict property at about 1900 GMT on Friday.
Two fire engines attended the blaze at Bray Street.
The police said they believe local youths may have been responsible for the attack.
The same officer was hurt in a hammer attack less than a year ago.
When you get youths who are intent on attacking them morale will fall and the crews will be reluctant to go back into those areas
The Fire Brigades Union has appealed to community workers and parents to try to ensure that children do not get involved in attacks on the emergency services.
Union official Jim Quinn said attacks on firefighters were a problem throughout the city.
"There's a thuggish element everywhere in the city that just seems hell-bent on abusing firefighters and ambulance workers.
He said they were trying to make people understand that the fire brigade and ambulance service were vital to their communities.
District Commander Leonard Entwhistle appealed to local people to help solve the problem.
"Obviously the fire crews are eager to carry on with their job and when you get youths who are intent on attacking them, morale will fall and the crews will be reluctant to go back into those areas.
"So it is a matter now of appealing to the communities to stop these mindless attacks.
"We are there to help them."
Detectives have appealed for anyone with information about the attack to contact them.