Beijing  - Three children died and 28 were injured after heavy snow caused the roof of a canteen to collapse at a primary school in northern China, state media said Thursday, as more snow and freezing temperatures caused havoc in many areas.

In the worst-hit province of Hebei, the canteen roof collapsed at the Longfeng Private Primary School in Yongnian county as the children were eating dinner Wednesday evening, the official Xinhua news agency said.

Two girls and a boy were killed while hospitals were treating the 28 injured children, the agency quoted local officials as saying.

After the accident, the county government ordered all schools to suspend classes pending safety checks.

The collapse followed two days of continuous snow in the area, which recorded its heaviest snowfall since 1955.

All major roads were closed in Shijiazhuang, the nearby provincial capital, as authorities and local residents worked to clear the snow.

Many flights were also cancelled from Tuesday in Hebei, nearby Shanxi province and the Chinese capital, Beijing.

At least one more person died in a building collapse caused by snow in Shijiazhuang while several deaths were reported in traffic accidents, state media said.

Tens of thousands of passengers were stranded at airports and at least 30,000 other travellers were stranded as many vehicles were stuck in deep snow on roads in rural areas, the reports said.

Meteorological officials in Shijiazhuang recorded 7.44 centimetres of snow in 24 hours by early Wednesday with accumulated snow up to 48 centimetres deep in some areas.

The Shanxi provincial government dispatched 16,000 traffic police officers to supply food and water to stranded road passengers, the agency quoted Wang Wenxi, provincial police official, as saying.

The national meteorological office issued an orange alert for snow on Wednesday, forecasting more heavy snow in several areas of northern, central and eastern China Thursday. (dpa)