One of the operators of the Swiss bar in which 40 people died and more than 100 were injured on the New Year’s Eve has been place under arrest, according to local media.

Prosecutors are investigating the French owners on suspicion of ‍crimes including homicide by negligence, while victims’ families have filed legal complaints over the blaze at the “Le Constellation” bar in the town of Crans-Montana.

The owners, Jacques and Jessica Moretti, did not ‌answer reporters’ questions as they entered the prosecutors’ office in the nearby town of Sion on Friday, ⁠which Swiss authorities have designated a national day of mourning over the ‌disaster.

Eyewitness video on social media appears to show the moment a fire broke out inside Le Constellation bar in Crans-Montana, Switzerland.

The ​couple ‍have expressed their grief over the fire and said they would co-operate fully with the investigation. More than half of the 40 people who died in the blaze were teenagers and a further ⁠116 people were injured, many of them seriously.

“We are devastated and overcome with ⁠grief, our thoughts are constantly with ⁠the victims, their loved ones who have been bereaved so brutally and prematurely, and all those who are fighting for their lives,” they ‍said on Tuesday.

Prosecutors said last weekend that the legal criteria to detain the couple had so far not been met.

Witnesses and prosecutors have said the blaze appeared to have been started by the use of sparkling candles that set foam soundproofing on the basement ceiling alight.

Questions remain about oversight at the bar, which the ‌local mayor admitted this week ‌had missed multiple safety checks.

Twenty-one of the dead were from Switzerland, seven from France, and six from Italy. There was also a ‌Swiss-French dual national and a French-British-Israeli national.

The presidents of France and Italy are expected to ⁠attend Friday’s ceremony in the nearby town of Martigny in memory of the victims.