A blast caused by a fire at a weapons storage depot in eastern Baghdad on Friday set off rockets that hit neighboring districts, killing at least four residents and injuring 14 others, police and hospital sources said. Video footage showed a large plume of smoke rising above the depot. A huge explosion was followed by a massive shockwave. Women and children were heard screaming in the background. Footage of the blast site showed a massive crater almost five meters (15 foot) deep and 20 metres wide. Many surrounding buildings and vehicles were heavily damaged. The depot belonged to one of the Shi'ite paramilitary groups of the Popular Mobilization Force (PMF), a police officer said. The PMF is a coalition of mostly Iranian-backed militias that are fighting Islamic State, the hardline Sunni group that overran swathes of northern and western Iraq two years ago. The rockets set off from the depot damaged houses, shops and cars at eight locations, and started a fire at a flour factory that was still burning two hours after it was hit, the police officer said.