Police say two girls aged 1 and 11 have suffered serious burns after a petrol bomb was thrown through the living room window of their family home in the southeast Irish city of Waterford.

No group claimed responsibility for Thursday night's attack. Police say they arrested a man in his mid-20s on suspicion of involvement.

Waterford politicians say the family could have been targeted as part of a criminal feud in the city. They say the targeted family has suffered criminal intimidation in the past.

Neighbors said a grandmother in the family used a fire extinguisher to put the out the flames. Both girls were hospitalized in serious but not life-threatening condition.

Ireland's gangland underworld is rife with turf wars, and civilians sometimes get caught in the cross-fire.