Local government officials in China's Sanhe county, near Beijing, said on Thursday they had started an investigation into the cause of a massive explosion at a shop selling fried chicken that left 7 dead and 27 injured.

Officials said that 14 people had been discharged from the hospital, and that the initial indications were that a gas leak had caused the blast.

Last year, President Xi Jinping ordered a safety overhaul across China, calling on all regions to rectify safety risks and "hidden dangers" after 31 people died in a gas explosion at a barbecue restaurant.

The explosion on Wednesday at a fried chicken shop, in the town of Yanjiao in China's northern province of Hebei, caused a massive orange fireball. The force ripped off the fronts of several buildings, crumpled cars on surrounding streets and left large pieces of debris on fire.

On-site rescue work has ended, cleanup at the scene is still ongoing and an investigation has begun, officials said in a statement.