A teenager has been released on bail pending further inquiries by police investigating a gorse fire on Cave Hill.
The fire was first reported at around 9.20pm on Wednesday evening.
Crews from the NIFRS remained on-site overnight before eventually bringing the blaze under control by Thursday afternoon.
The boy was detained in west Belfast on Thursday on suspicion of arson.
PSNI Chief Inspector Fox said: “Lighting uncontrolled gorse fires is highly irresponsible and has the potential to cause widespread damage to the environment and harm to wildlife, as well as threatening homes, farms and the people living in those areas.
“The unpredictability of fire can also mean that those causing them may be putting their own lives at risk as well as the lives of the fire service personnel and other emergency services tasked to deal with them."
He added: “Police will be proactive in robustly investigating such reports and would urge landowners and members of the public to be vigilant and report any suspicious activity to Police through 101, online or in an emergency 999.”