Updated at 10:48 a.m. ET

An explosion ripped through a kindergarten in eastern China on Thursday, killing at least seven people and wounding dozens more, according to the country's state-run media. The blast hit the front gate of the building as parents and grandparents were picking up their children after the school day.

It's not immediately clear what caused the explosion or how many children are among the victims — though Global Times, a state-run media outlet, cites a witness who blamed the explosion on a "gas cylinder at a roadside stall."

The newspaper People's Daily, which posted graphic photos and videos of the chaos after the blast in Fengxian, reports that an investigation is underway.

Shortly after the explosion, images began to circulate on social media appearing to depict a chaotic scene strewn with bloodied bodies and bent metal.

"Videos purportedly shot in the aftermath of the explosion showed children and adults lying on the ground, many bleeding," NPR's Rob Schmitz reports from Shanghai. "Clothes, shoes and other items were strewn about beside pools of blood."

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