At least 42 people, most of them pensioners on a day trip, have been killed in a head-on collision between a bus and a truck in south-west France.

The crash happened on a country road near Puisseguin in the Gironde wine region, east of Bordeaux. Both vehicles then caught fire.

France's president said he had been "plunged into sadness by the tragedy". PM Manuel Valls is at the scene.

It is the worst French road disaster since 1982, when 52 people died.

The bus collided with the timber truck at 07:30 local time (05:30 GMT), at what local residents described as a notoriously dangerous bend in the road.

Both vehicles quickly caught fire.

The French government said 42 people had died and nine people were injured, four seriously.

Most of the dead were the elderly passengers who become trapped in the bus. It was not clear if the bus driver was among the dead. The lorry driver was originally included in the death toll, but unconfirmed reports say he may have managed to escape.

#UPDATE: At least 42 dead in French pensioners coach crash - latest from near Bordeaux https://t.co/tYQ2aQjHYI pic.twitter.com/EU2fWReaVF

— Agence France-Presse (@AFP) October 23, 2015

Most of those on board the bus were reported to have been members of an elderly people's association from the small town of Petit-Palais-et-Cornemps, which has a population of just 700, along with others from neighbouring communities.

They had not long left on their journey, and were heading south for a day trip into the Landes region.

Marie Fulbert, a council official from the nearby town of Libourne, said they were still waiting for news of who was on the bus and said they had taken "a lot of calls from friends and family".

More than 60 firefighters attended the scene. The wounded were airlifted to hospital.

The exact cause of the crash is not yet clear.

Hollande, who is on a visit to Athens, has promised a full investigation into what he called an "immense tragedy".