The Sabah Daily reported that the incident took place in the crude oil furnace of the refinery, located in the Aliaga district.
The blast was felt in the district center, with surrounding residential areas reportedly shaken by the force of the explosion, the report said.
A fire broke out shortly after the explosion, the daily reported, adding that many ambulances and firefighting teams have been dispatched to the scene for rescue work.
The cause of the explosion remains unclear, the daily added, without providing details on any casualties.
The Turkish Petroleum Refineries Corporation is a leading player in the country's energy sector, with its four refineries' annual crude oil processing capacities totaling 30 million tons.
MP/PR