MOSCOW (AP) — A fire at a private nursing home in the Ukrainian city of Kharkiv killed 15 people and injured five others Thursday, officials said.

The cause of the blaze in the two-story building was under investigation.

News reports said the building originally was a residence but had been converted into a nursing home and that it was unclear if it had been registered for that function.

The Interfax news agency cited Kharkiv police as saying the home’s owner and employees were being questioned.