A fire at an Istanbul nightclub during renovations on Tuesday killed at least 29 people, officials and reports said. Several people, including managers of the club, were detained for questioning.

At least one person was being treated at a hospital, the Istanbul governor’s office said in a statement.

The Masquerade nightclub, which was closed for renovations, was on the ground and basement floors of a 16-story residential building in the Besiktas district on the European side of the city bisected by the Bosphorus. The fire was extinguished.

Gov. Davut Gul told reporters at the scene that the cause of the fire was under investigation and the victims were believed to be involved in the renovation work.

Authorities detained five people for questioning, including managers of the club and one person in charge of the renovations, Justice Minister Yilmaz Tunc said.

Mayor Ekrem Imamoglu said authorities were inspecting the entire building to assess its safety.

Several firefighting and medical teams were dispatched to the scene, he said.