A young family has been left badly shaken after being rescued from a house fire started by sectarian arsonists.
The attack on the Newtownards home of a 38-year-old woman and her three children is the third in two weeks.
Police investigating the incidents have arrested a 32-year-old woman on suspicion of intimidation.
Over the last two weekends sectarian graffiti was daubed on the walls and windows of the family's semi-detached house in Lenamore Park.
But the campaign of intimidation escalated in the early hours of Friday when the house was set alight. It is understood flammable liquid was poured through the front door letter box and ignited at around 2am.
Family members, awoken by smoke alarms, were rescued by firefighters, police officers and a neighbour.
Police and the neighbour climbed on to an adjoining flat roof to save the woman's two daughters, aged 12 and seven, and her two-year-old son. Firefighters entered the property and brought the woman to safety.
The attack has prompted widespread condemnation. Newtownards PSNI Area Commander Michael McDonald said the family was fortunate to escape without injury.
"This was a particularly reckless and cowardly attack which could have had more serious consequences than fortunately we have," he said.
Ulster Unionist leader and Strangford MLA Mike Nesbitt said the attack was a murder attempt. "It was only thanks to the swift action of a neighbour and the police that a mother and three children were rescued and tragedy was averted," he said.