Two properties were evacuated and neighbours told to stay indoors after a car fire spread to a property and damaged the mains gas supply.
Two Mitsubishi Colts were set alight at around 7,30am on Saturday. The blaze melted guttering of a nearby house and damaged window pains and a wooden garage.
Rotherham firefighters found the suspected gas leak on Goldsmith Road, East Herringthorpe and called for engineers to make the scene safe.
Anyone with information about who started the fires should call Crimestoppers, anonymously, on 0800 555 111.