The blasts sent a giant fireball into the sky and forced residents to flee the Atomic Junction area, in the north-east of the city, officials say. The incident happened at about 19:30 GMT on Saturday. Reports suggest a tanker delivering natural gas caught fire.
Three people were confirmed killed, and at least 30 others were injured. The first blast reportedly triggered a second explosion and a fire at a petrol station nearby. The blaze, in the suburb of Legon, was later largely brought under control, government minister Kojo Oppong Nkrumah told local radio, according to Reuters news agency. Many of those evacuated were students at the University of Ghana, which is sited in the area.
In June 2015, about 150 died in a fire at a petrol station in the city.