ACCRA (REUTERS) - A natural gas station in Ghana's capital Accra exploded on Saturday evening (Oct 7), sending a giant fireball high into the sky above the city as frightened residents fled the scene, a Reuters witness said.

At least six fire trucks and several ambulances responded to the blast at the city's Atomic Junction near the University of Ghana. It was not immediately clear if there were casualties.

The explosion at around 7.30pm local time (3.30 on Sunday, Singapore time) began at a station that sells liquefied natural gas and spread to a petrol station across the street, the witness said.

An explosion at a petrol station in Accra in 2015 killed around 100 who had sought shelter nearby from flooding in the country's worst disaster in more than a decade.

Infrastructure in Accra, a city of roughly seven million people, has failed to keep pace with population growth after years of rapid economic expansion.