THESSALONIKI — Fire broke out Wednesday morning in the COVID-19 ward of a hospital in the northern Greek city of Thessaloniki, leaving one person dead and two seriously injured, firefighters said.

The fire department said it had evacuated 34 patients from the COVID-19 ward of the Papanikolaou hospital.

Another four of those evacuated had already been in serious condition due to the coronavirus, and were under increased monitoring, authorities said. The body of one person was found on the second floor, the fire department said.

It was unclear what sparked the blaze. Video footage from the site showed thick black smoke billowing out of two windows on a lower floor of the facility and firefighters clambering up to the windows.

Thirty firefighters with 11 firefighting vehicles battled the blaze, which appeared to have been extinguished by mid-morning.