A 72-year-old man killed five people in Ukraine's western Rivne region using an axe and a hammer in a facility for internally displaced people, police said on Tuesday.
The motive of the attack was unclear but the police said it was "a domestic conflict" that "escalated into a fight" between the residents of a former school building now housing refugees from eastern and central Ukraine.
"During the altercation, the man began striking five people with a hammer and an axe," the Rivne region police said on social media.
The attack happened in the early hours of Tuesday, police added.
"As a result of the injuries sustained, five citizens died at the scene: men aged 60 and 68, two women aged 81 and 78 from Donetsk region, and a 56-year-old native of Kirovograd region."
Images posted by the police showed a large hole in the door leading to one of the rooms and traces of blood on an axe and on the building's floor.
The suspect, himself a refugee from the embattled Donetsk region in Ukraine's east, has been detained and a probe has been opened into premeditated murder, the prosecutor general's office said.