An explosion rocked a factory in Luqa industrial estate late on Thursday night, sparking flames which were put out by firefighters before they spread further.
Police received reports of a fire at the site on Triq l-Ingiered at around midnight. Luqa residents reported hearing the rumble of an explosion.
Squad cars and Civil Protection Department personnel were dispatched to the site.
A police spokesman said that nobody was at the site at the time and that the flames were put out by firefighters without further incident.
A police investigation is under way.
An eyewitness shot video of the fire.