The alarm was sounded at 05:25 local time by one of the injured on the slopes of Mont Maudit.
Foreigners are thought to be among the victims. The injured were airlifted to a local hospital.
The mountain is known as a popular route for summer tourists heading for the summit of Mont Blanc.
The climbers are believed to have been roped together in several groups when the avalanche struck.
About 28 climbers from several countries are said to have taken part in the expedition, and reports say a number of them are still missing.
Rescue teams are using a helicopter and heat-seeking device to try to locate the missing.
The local authorities described the avalanche as “the most deadly” in recent years, according to the AFP news agency.
Mont Maudit – meaning the cursed mountain – is the third-highest peak in the Mont Blanc massif range, rising to 4,465 m (14,650 ft).
A news conference in Chamonix is expected shortly.
At least 158 people have died in Spain's worst flooding disaster in generations. On October…
Google has been fined two undecillion (a two followed by 36 zeroes) roubles by a…
Embarking on a home remodel is an exciting journey, promising enhanced comfort, increased property value,…
The US presidential candidates continued to campaign across key swing states on October 20. Footage…
Elon Musk has said he will give away $1 million a day to a registered…
India and Canada have decided to expel their top envoys along with other diplomats as…