Two separate pipe bomb attacks have taken place in Dublin overnight.
Gardaí were called to Glenhill Avenue in Finglas shortly before 2am where they found a pipe bomb device that had exploded under a car.
The car was damaged but no one was injured in the blast.
Earlier, a device was thrown through the window of a house in Dublin city centre.
Army bomb disposal experts examined the device at First Avenue off Seville Place, in the north inner-city, after they were called to the scene just after midnight.
The device was outside a house on the street, having been thrown through a window and ejected out the same window by those inside.
The bomb disposal officer examined and made safe the device at the scene and removed it to barracks. It was found to have been viable.
The device has been handed over to gardaí for ongoing investigation. The team gave the all clear at Seville Place at 1.20am.
There have been four such attacks reported in Dublin this week.
Earlier this week, a pipe bomb exploded outside a house on Monasterboice Road in Crumlin on Wednesday night.
On Thursday night a hoax nail bomb was found under a parked car on Kildare Road in Crumlin.
Garda investigations are continuing; they have not confirmed at this stage whether these pipe bomb attacks are connected.
Elsewhere, police in Armagh city are investigating a pipe bomb attack at a house early this morning.
The alarm was raised around 5am when the PSNI received reports of a loud bang at Ballynahone Crescent.
No one was injured, but the front porch and some roof tiles were slightly damaged in the explosion.
British army bomb experts were sent to deal with the device.
A number of items were taken away for further examination by forensic scientists.
Detectives have appealed for anyone with information to contact them.