The blaze was driven in part by explosions, according to the country’s prime minister, Zoran Zaev, who immediately launched an investigation. The prime minister’s office said the cause of the fire had yet to be determined, and that three days of national mourning had been announced.
Oxygen tanks being used to treat patients with severe Covid-19 have been blamed for deadly fires at other coronavirus clinics around the world. In July, at least 39 people were killed at a hospital in southern Iraq after an oxygen tank explosion in a ward where Covid-19 patients were being treated. In April, a fire caused by an oxygen tank explosion at a coronavirus hospital in Baghdad killed at least 82 people.
Sasho Trajcevski, the deputy commander of the Tetovo fire department, told the local television station 360 that the plastic elements in the modular building had driven the flames.
In a statement posted on social media, Mr. Zaev called the fire a “great tragedy” and offered his condolences to the families of the dead.
“The fire has been extinguished, but many lives have also been extinguished,” he said, while adding that emergency workers had done their best to save lives.