The cause of the fatal fire in an improvised Covid hospital in North Macedonia was initially still unclear on Thursday.
In the fire that broke out on Thursday night in the north-west Macedonian city of Tetovo, 14 patients were killed and twelve others were injured.
Hospital staff were not injured.
North Macedonia's Prime Minister Zoran Zaev spoke of a "great tragedy" and made it clear that the fire was triggered by an explosion.
However, he did not comment on the question of how the explosion came about.
The government said that the causes are still being investigated.
Michael Martens
Correspondent for Southeast European countries based in Vienna.
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According to unconfirmed reports by Macedonian media from Tetovo, an exploded oxygen tank could have started the fire.
Local media also reported that there had been difficulties with the oxygen tanks and the associated pipes last month.
However, these reports have not been officially confirmed.
Three days of mourning proclaimed
The burned down hospital was a makeshift facility made up of several containers, in which the fire spread at great speed, according to several eyewitnesses.
The twelve surviving patients were transferred to other hospitals.
The city council of Tetovo, a place populated by the majority of Albanians, has declared a three-day mourning period.
The now burned down hospital was only built in April. There are more than a dozen such makeshift hospitals for Covid patients in the country. They were built with grants from the World Bank. As in all Balkan countries, the vaccination rate is extremely low in North Macedonia. So far, barely 26 percent of the approximately two million inhabitants of the southernmost republic of the former Yugoslavia have been fully vaccinated.