Authorities said one of the survivors was sent to a hospital with serious injuries.
French Prime Minister Elisabeth Borne arrived at the scene on Wednesday afternoon. She said she wanted to show the government’s support for the families of the victims and for the firefighters and rescuers on site.
Lt. Col. Philippe Hauwiller, who was leading the rescue work of firefighters, said the fire likely started on the home’s upper floor.
The ground floor was made of stone and the upper part of the building was built of wood with heavy timbers in the traditional style of the region, which might partly explain why the fire spread so quickly.
The local administration of the Haut-Rhin region said the fire broke out at 6.30am Christophe Marot, the secretary general of the local administration, said on news broadcaster France Info that 10 people with disabilities and a person accompanying the group were believed to be among the dead.
Many of the visitors came from the city of Nancy in eastern France, a statement from the Haut-Rhin prefecture said.
No other information about the victims was provided.
Fire officials at the scene said that while the fire quickly engulfed the structure, it likely had been smoldering unseen. Video showed flames lapping above a ball of fire on the second floor.
The owner of the devastated home, who lives across the street, gave the alert, saw the fire and heard the screams, the deputy prosecutor said. She was in shock but answered initial questions from investigators, French media reported. The owner was not identified.
The fire department deployed 76 firefighters, four fire engines and four ambulances to contain the blaze and treat the victims. Forty police officers were also mobilised. The fire was brought under control on Wednesday morning.
French President Emmanuel Macron wrote on X, the social media platform formerly known as Twitter: “In the face of this tragedy, my thoughts are with the victims, the injured and their families. Thank you to our security forces and emergency services.”
Mathieu Klein, the mayor of Nancy, where a group of the vacationers hailed from, insisted in an interview with BFM TV station that the tragedy should not put an end to such vacation excursions.
“The right to vacation is a fundamental right, above all for these people” living with handicaps, he said.
The fire was the deadliest in France since an August 2016 fire that killed 14 people in a basement nightclub in the city of Rouen.