Belgium plans national day of mourning after coach crash kills 28, including 22 schoolchildren

28 people, including 22 schoolchildren, have been killed after the coach in which they were travelling slammed into a tunnel wall in the Swiss Alps.

The dead were made up of 21 Belgians and seven people from the Netherlands, with a further 24 people hospitalised after the head-on collision. The injured included 17 Belgians, three Dutch and one person from Poland and Germany respectively.

The crash took place shortly after 9pm last night on the A9 highway near the town of Sierre, not far from the Swiss border with Italy.

Police said the bus was carrying 52 people, mostly 11 and 12-year-old students from two different Belgian schools returning to the towns of Heverlee and Lommel after a skiing trip in Val d'Anniviers.

As Belgium announced plans to hold a national day of mourning to mark the tragedy, distraught parents flew to Switzerland with some still unsure about the fate of their children.

"It is a black day for all of Belgium," said the Belgian Prime Minister Elio Di Rupo.

In a statement, Swiss police said "The bus hit the barrier stones on the right side of the road. It then hit the tunnel wall head on in an emergency stop space…Because of the strong impact the bus was badly damaged and several passengers were trapped in the wreckage."

Christian Varone, the police chief in the Swiss canton of Valais, told a news conference that rescuers were greeted by what he called "a scene like a war."

"We have had a number of serious accidents in Valais but nothing like this, with so many young victims," he added.

The A9 highway was closed in both directions to aid the rescue, with eight helicopters and 12 ambulances taking victims to hospitals. Dozens of police and firefighters, 15 doctors and three psychologists were also called to the scene.

Until today, the worst accident in a Swiss highway tunnel happened in 2001, when two lorries collided in the Gotthard tunnel killing 11 people.

One of Europe's deadliest tunnel accidents happened in March 1999, when 39 people were killed after a lorry caught fire in the Mont Blanc tunnel between France and Italy. The blaze burned for two days while firefighters tried to reach victims and vehicles trapped in the tunnel under Western Europe's highest peak.