The blast ripped through a factory site in the eastern harbor city of Ningbo early Sunday, filling the sky with gray smoke, Chinese state media reported.

Local officials said at least two people died and more than 30 others were wounded.

Later on Sunday, the People's Daily newspaper posted aerial images of the blast site on Twitter, showing wrecked buildings and an area filled with concrete debris. The group also noted that 14 people were still being treated in hospital for their injuries.

Footage broadcast on state television showed mangled cars, debris-littered streets and a number of collapsed buildings surrounding the site of the explosion. According to media reports, windows had been shattered in streets several hundred meters away from the blast.

Police said the residential buildings knocked down by the impact were vacant at the time because they were slated for demolition, adding that an investigation into the cause of the incident was underway.

Rescue workers comb through the rubble in Ningbo after a powerful blast caused a number of buildings to collapse

Explosions, fires and other industrial accidents are not uncommon in China, where safety rules often are not strictly enforced. The government has embarked on a campaign in an attempt to improve conditions, but many companies still flout the regulations.

In 2015, an explosion triggered by improperly stored chemicals killed more than 170 people in the northern port city of Tianjin, east of Beijing. A 2016 government inquiry into the accident recommended 123 people face punishment.

rs,nm/jlw (Reuters, AP, AFP, dpa)