A car was set on fire in the basement of a unit block in Wolli Creek overnight.
About 1.20am emergency services were called the unit block on the Princes Highway, after reports of a fire.
Police found a car well alight in the basement of the building.
Thirteen residents were evacuated with a woman, 46, taken to St George Hospital with smoke inhalation.
Anyone who saw anything suspicious in the area is asked to contact police or Crime Stoppers on 1800 333 000.