At least seven people were killed and dozens injured in an explosion at a nursery in eastern China, with official media saying it was caused by ‘gas cylinders’.

The blast happened near the entrance to the building in Fengxian, in Jiangsu province, as parents would have been meeting their children on Thursday afternoon.

Two people were killed at the site, while another five died at hospital, said an online post from officials at Xuzhou, which administers Fengxian.

Another 59 people were injured, including nine who were in a critical condition, said the post on Sina Weibo, China’s Twitter.

The post did not say how many children were among the casualties.

It wasn't immediately clear whether the explosion was deliberately set or the result of an acciden

Unverified photos purportedly from the scene and posted on social media showed children and adults lying on the ground, some bleeding.

One of the victims appeared to have all his clothes burned off, while others sat in shock. Some lay on the floor appearing dazed, and one woman was cradling a crying child.

Police said the blast struck at the Chuangxin Kindergarten at around 4.50pm, the usual time that Chinese nurseries finish for the day.