A resident said a leakage on the main gas tank was suspected as the cause.
"The situation is very serious," regional police commander Yoosa Bonga told AFP of Thursday night's incident.
"We can't immediately say what caused the fire but we took several people to the 37 Military Hospital for treatment but unfortunately five people are dead."
A spokesman for the Ghana Fire Service, Billy Anaglatey, said "four bodies were retrieved from the streets and one on the premises of the gas station".
He said some of the victims were passers-by, adding that the fire also damaged a nearby school building.
A resident, Daniel Amissah, who had just left the gas station before the explosion, said a leakage on the main gas tank was suspected as the cause.
At least 150 people were killed in June last year when a petrol station in Accra caught fire, with heavy flooding contributing to the deaths as the blaze was believed to have spread from a nearby residence via fuel on the floodwater.
Many people had sought refuge from a seasonal downpour under the canopy of the petrol station when the flames ignited tanks, causing an explosion and deadly blaze.