"Several" people have been killed by a fire in a bar in the Swiss ski resort of Crans-Montana

The fire began at around 01:30 (00:30 GMT) in a bar called Le Constellation, police say

The cause is not known, although police initially said there had been an explosion. Local reports say there may have been pyrotechnics involved - but that is unconfirmed

A helpline has been set up for concerned families: +41 848 112 117

Emergency services are at the site and details are still emerging. Here's everything we know and don't know so far

Edited by Owen Amos, with Silvia Costeloe reporting from Crans-Montana

Silvia Costeloe Reporting from Crans-Montana

The bar where the fire happened is a real institution here. It's been around for at least 40 years.

It's a big bar and it's not posh. But this is quite a posh ski resort, there's quite a lot of luxury here - it was famous in the 1980s for hosting the World Cup skiing, and that's coming back.

A lot of the bars are luxurious, but the Constellation was not like that. It's a really big bar, it's got an upstairs with TV screens where people go and watch football matches.

Downstairs it just had a big bar where I suppose yesterday people would have been dancing and drinking.

You go there for beers - it's a kind of young bar. It would've been a mixture of young people, Swiss people, people coming up from the valleys to celebrate here in Crans-Montana.

There would have been a mixture of nationalities as well, you would think.

Silvia Costeloe Reporting from Crans-Montana

I’m standing at the police cordon - you can see behind me the site of this explosion.

In the last few minutes police have been putting up these white screens as they continue their forensic work.

So far the details coming out are very small. We don’t know the number of casualties yet - but there is a fear, caused by the size of this operation.

I spoke to some people who heard the explosion, who then heard hours of ambulances afterwards.

One man told me he actually wondered whether the ambulances were because people had drunk too much. But unfortunately, a scene of absolute chaos unfolded here last night.

I drove past Le Constellation bar just half an hour before the explosion happened - there were people in the streets. There’s a big valley here, and if you’re on any balcony you can see fireworks throughout the whole valley.

It’s just a real atmosphere of shock here today.