Police say a car was set alight in Elm Park in Richhill, Co Armagh. around 5.40 am this morning.
Officers said it appeared the car was deliberately pushed up against a house which also caught fire.
The occupants – two men, aged 65 and 30, and a 65-year-old woman – managed to leave the house safely.
A number of nearby homes were evacuated as a precaution while the Fire and Rescue Service dealt with the blaze.
Detectives are trying to establish a motive for the attack and have appealed for anyone with information to contact them on the 101 number.