Seven people have been killed and dozens more are reportedly injured in an explosion at a nursery school in China.

State media reported the blast tore through the area as children were being collected from school in the city of Fengxian in Jiangsu province at about 4.50pm local time.

Graphic mobile phone footage posted on social media show more than a dozen people lying motionless in front of the nursery’s steel sliding gate in the aftermath of the explosion.

One image shows a woman clutching a sobbing child as paramedics treat the wounded.

Frantic calls to the nursery and the hospital were going unanswered, according to the AFP news agency.

Two people died at the scene and five died in hospital, according to Chinese Central Television. It is not yet clear if children are among the dead. At least 66 people are reported to have been injured.

Images show the force of the blast had torn the clothes from some of those lying motionless on the ground.

It is unclear at this stage whether the blast was an accident or a deliberate act.

“The police and related departments rushed to the scene as soon as it was reported and conducted rescue and investigation work on the site,” police said on Weibo, a Chinese social media platform similar to Twitter. “Currently, the investigation work is still underway.”

The newspaper Xiandaikuaibao on its website cited an unidentified witness as saying the blast appeared to have been caused by an exploding bottle of cooking gas.

The blast is the latest tragedy to strike a nursery in the communist country, where there is now a two-child-per-family policy after the government relaxed its one-child policy.

A school bus carrying children to nursery burst into flames inside a tunnel in Shandong province on 9 May, killing 11 children, a teacher and the driver.

Officials said the fire was started deliberately by the driver who was angry at losing his overtime pay.

Kindergartens in the country have been targeted previously in apparent revenge attacks carried out by people bearing grudges against their neighbours and society.

China maintains tight control over firearms and most attacks are carried out using knives, axes or homemade explosives.

Fengxian is in eastern China’s Jiangsu province, about 370 miles (595 km) northwest of Shanghai.