CHAMONIX, France- A climber trying to scale Mont Blanc may accidentally have caused a slab of ice to snap off today high in the French Alps, sparking an avalanche that swept nine climbers to their deaths.

A dozen climbers were injured and two were still missing by nightfall.

When the slab of ice broke off, it sent a wall of snow sweeping across the face of the mountain.

Hikers were making the ascent, all roped together.

It was the deadliest avalanche there in recent years.

Officials had warned climbers to be careful because of the unusually snowy spring, but there were no specific fears an avalanche would happen.

No Americans are among the dead and injured.

Four climbers thought missing had decided not to go with the group.