28, mostly children, killed in Swiss bus crash

By Diana Magnay, CNN

March 14, 2012 -- Updated 0909 GMT (1709 HKT)

Dozens killed in Swiss bus crash

STORY HIGHLIGHTS

• NEW: "This is a tragic day for Belgium," prime minister says
• Most of the children were 11 or 12 years old
• The bus was carrying 52 people, police say
• It was on its way back to Belgium from a ski trip, they say

(CNN) -- A bus crashed into a tunnel in Switzerland, killing 28 people, including 22 children, Tuesday night, police said.

Another 24 children were injured in the wreck, police said.

Most of the children were 11 and 12 years old, said Joren Vandeweyer, a spokesman for the Belgian Ministry of Foreign Affairs.

The bus was on its way back to Belgium from a ski trip. It slammed into a highway tunnel in Sierre in the Swiss canton of Valais.

The bus was carrying 52 people in total: two bus divers, four other adults and 46 children.

The cause of the crash is under investigation.

Belgium made available two military planes to take parents to see their injured children and to bring them back, Vandeweyer said.

"This is a tragic day for Belgium," Belgium's Prime Minister Elio Di Rupo said, adding he will be traveling to Switzerland Wednesday.

CNN's Stefan Simons and Samira Said contributed to this report.