The families of teenagers missing after a fire at a bar in a Swiss ski resort are facing an agonising wait for news and appealing for information about their loved ones online.

The fire in Crans-Montana was likely caused by sparklers placed on bottles of champagne that came “too close to the ceiling”, Swiss officials told a news conference on Friday.

An investigation into the fire will focus on the materials used at the site, the bar’s fire safety measures, its capacity and the number of people inside at the time, Valais Attorney General Beatrice Pilloud said.

Swiss authorities have said it could take days if not weeks to identify the victims of the fire, which killed 40 people and injured another 119. Officials said 113 of the injured had been identified, with authorities still working to identify the other six.

In the meantime, families and friends have been taking to social media to appeal for information about their loved ones who were at the bar that night.