R.I.P.: A former student weeps at the school in Belgium where many of the children in this class photo were among the 28 victims of the Swiss crash. (EPA)

(Reuters)

R.I.P.: A former student weeps at the school in Belgium where many of the children in this class photo were among the 28 victims of the Swiss crash. (
)

SION, Switzerland — Many of the happy youngsters pictured above perished when their bus slammed head-on into a concrete wall in a Swiss Alps tunnel, killing 28 people, mostly children from two schools who were returning from a ski vacation.

Swiss police said Wednesday the vehicle was not speeding and everyone was wearing seat belts.

The bus was carrying students about age 12 from two Belgian schools when it crashed shortly after 9 p.m. Tuesday night on a highway near the southern town of Sierre, Switzerland.

The horrific accident in the short Tunnel de Geronde left the front of the bus mangled, trapping people inside. Twenty-two schoolchildren and six adults including the driver were killed and another 24 children were hospitalized in what the police chief described as a “scene like a war.”

Belgium flew anxious parents and relatives to the site and called for a day of mourning.

Authorities were still trying to work out how a modern bus, a rested driver and a safe tunnel could add up to such a tragedy.

Video cameras in the tunnel captured the accident, a Swiss prosecutor said. Olivier Elsig, prosecutor for the canton of Valais, told reporters the children on the bus were wearing seat belts, no other vehicle was involved, and the bus was not speeding.

Investigators were looking at three possible causes for the crash, he said — a technical problem with the bus, a health problem with the driver, or human error.

An autopsy will be performed on the driver. The seat belts wouldn’t have helped much due to the severity of the crash, Elsig said.

“We will examine everything to find out what happened,” Elsig promised.

Dr. Jean-Pierre Deslarzes, medical director of the cantonal rescue service OCVS, said rescuers were traumatized because so many of the victims were children.

“We found an apocalyptic situation when we arrived,” said Christian Varone, the police commander for Valais, who called the tunnel “safe.”

Police said 21 of the dead were Belgian and seven were Dutch. Of the injured, 17 are Belgian, three are Dutch, one is German, one is Polish, and two others have yet to be identified.

Deslarzes said 14 of the injured remain in a hospital in Sion, one in intensive care, but none of them had life-threatening injuries. Three others were taken to Lausanne University Hospital with serious injuries, he said, while another child was in a hospital in Bern.

The crash occurred in a stretch of tunnel where the speed limit is about 60 mph. The bus veered, hit a curb, then rammed into a concrete wall, police said. The highway was closed in both directions as 200 rescuers were called to the scene.