A teenager educated in Britain is among those missing after a deadly fire in a Swiss ski resort.

Charlotte Niddam, 15, lived in Bushey, Hertfordshire, until recently and attended Immanuel college, a private Jewish secondary school in the town. The school issued a statement on Friday saying it was “praying for a miracle for Charlotte”.

It is understood her family have not heard from her since disaster unfolded in a crowded bar in Crans-Montana in the early hours of New Year’s Day. Many of those celebrating at Le Constellation bar when the fire took hold were teenagers.

Swiss authorities said on Friday that 40 people had died and more than 100 had been injured. Some casualties have yet to be identified.

The Niddam family sold their British home in March. Charlotte’s former school confirmed they had moved back to their native France.

A memorial near Le Constellation bar on Friday. Photograph: Denis Balibouse/Reuters

Charlotte appears to have regularly spent time in Crans-Montana, which is about 62 miles from the French border. She has advertised her services as a babysitter on the ski resort’s website, saying she is often in the town and able to work at weekends and during school holidays.

A spokesperson for Immanuel college said: “We are reaching out with an urgent request for our school community to come together in support of Charlotte Niddam.

“Charlotte was a student at Immanuel college, and her family have now moved back to France.

“The families have asked that we all keep them in our thoughts and prayers during this extremely difficult time.

“We are all praying for a miracle for Charlotte and the others, and want the families to feel the full strength of the Immanuel college community’s support.”

Swiss authorities said on Friday that the fire was likely to have been started when fountain sparklers mounted on champagne bottles set the ceiling alight about 1.30am local time on Thursday.

Families of many of those missing have used social media to appeal for information. The resort is popular with tourists from mainland Europe and most of those affected are Swiss, French and Italian.