The evacuation of 100 people from their homes in Dublin overnight was due to a grenade explosion.
The explosion was previously thought to have been made by a pipe bomb, but the Army says the blast was caused by a suspected grenade.
The attack is believed to be linked to an ongoing feud which reportedly involves a man with connections to the INLA.
Around 100 people were evacuated from their homes after a device was thrown at a house near an apartment block on Park Terrace Street in the Coombe just before midnight.
It caused minor damage but no injuries.
Gardaí decided to evacuate a number of nearby homes after being told there were a number of other devices on the street.
After several hours of searching, no more bombs were found, but a controlled explosion was carried out on a suspect bag in the car park of the Carman's Court apartment complex which turned out to pose no threat.
Residents were subsequently allowed to return to their homes at around 6am.