Gardaí in Limerick believe a spate of arson attacks on houses in the Moyross estate may be linked to a feud taking place in the area.
Petrol bombs were thrown into two houses in College Avenue, Moyross, at 11pm on Thursday, causing substantial damage.
Both houses were unoccupied at the time, and nobody was injured in the attacks.
It is understood that the family of a young man injured in a shooting last month in the Moyross area was living in one of the houses.
His brother is one of 11 people to have lost their lives in the feud which has been ongoing since 2000.
Also on Thursday, a petrol bomb was thrown at a house in Craeval Park, Moyross, at 8.30pm.
The house was occupied at the time, but nobody was injured.
A family in the Pineview Gardens area of Moyross also escaped injury when their house was targeted at 2.30am yesterday.
Thursday night's violence came just 48 hours after two houses were fire-bombed in Pineview Gardens on Tuesday night.
Nobody was injured in those attacks, but the houses were destroyed.
A third house in the same estate was also targeted in the early hours of Wednesday, but it was not seriously damaged.
Meanwhile, investigations are ongoing into the stabbing of a man in the Pineview Gardens area on the same night.
The man suffered injuries to his neck, and was treated at the Mid-Western Regional Hospital in Dooradoyle.
The hospital has described his injuries as "not life-threatening".
Anybody with any information on the crimes is asked to contact gardaí at Mayorstone on (061) 456980.