A blaze said to have been started when the oil tank of a house was set on fire could easily have killed someone, a politician who viewed the scene has said.
Police, who are treating the fire as suspicious, said they received a report at 4.30am that an oil tank had been set alight at Manor Park in Newtownards.
Emergency services arriving at the scene found up to three oil tanks on fire, with the flames damaging nearby buildings and cars.
There were no reports of serious injuries but a number of people suffered from the effects of breathing in smoke, and fire crews had to fight to prevent burning oil from reaching other properties.
Fire crews said the flames destroyed two cars and a garden shed containing budgies, while four houses were damaged. They also said they were faced with flowing oil that was alight and could have spread to other homes had it not been dealt with in time.
Junior minister Jonathan Bell, who represents the area and who viewed the damage, said: "This is a disturbing incident. It requires a focused and determined police response and I am calling on people who can assist the police to do so immediately.
"It is too horrific to contemplate what could have happened here and the reality is that the potential of suspicious fires is to cause serious injury or, worse still, fatalities. That is why this investigation must be prioritised."
Strangford MLA Mike Nesbitt said: "This was an extremely serious incident which could easily have resulted in a tragedy.
"I am concerned that the police are treating this as suspicious because that would suggest they believe this fire was deliberate.
"If this is the result of deliberate action then the person responsible must be caught as soon as possible because someone could have been killed."