The explosion in Karachi was the result of short circuiting inside a room where the electric system is controlled, according to Nasir Aftab, who is deputy-inspector general for the city’s police. Broken glass hit customers who were waiting their turn to get fuel, he said.

Aftab said the blast was not sabotage, but officers were still investigating.

Karachi is the capital of southern Sindh province, where such incidents are rare.