An explosion has struck a nursery in eastern China, with local government saying at least seven people have been killed. It is unclear if any children were part of the fatalities. 

At least 59 people, including children, were injured.

The blast occurred as children were being picked up from the school in the city of Xuzhou in Jiangsu province on Thursday, police said.

Photos purportedly from the scene and posted to social media showed children and adults lying on the ground, some of them bleeding.

One woman is clutching her child, who is in tears. The force of the blast tore the clothes off some of the people lying on the ground.

It was not clear whether the explosion was an accident or was deliberately set.

WATCH: the moment the explosion went off

Huge explosion at a kindergarten in Fengxian in eastern China. At least 7 dead, 59 wounded. Blast occurred when children were leaving. pic.twitter.com/GFmxk0XaAz

— Behind The News (@Behind__News) 15 June 2017

China blast kills seven at nursery in Xuzhou pic.twitter.com/gN7or3cuDP

— Salt TV (@SaltTelevision) 15 June 2017

The newspaper Xiandaikuaibao on its website cited an unidentified witness as saying the explosive appeared to have been a bottle of cooking gas.

Calls to the kindergarten and local hospitals rang unanswered, AP news agency reported.

An official at the police station in Fengxian county told AFP news agency that the explosion was under investigation.

It is the latest tragedy to strike a nursery in China in recent weeks.

A school bus packed with kindergarten pupils erupted in flames inside a tunnel in eastern Shandong province on May 9, killing 11 children, a teacher and the driver.

Officials later said the fire was intentionally set by the driver, who was angry at losing overtime wages.