Forensic experts have identified the 14 victims of a fire in a COVID-19 field hospital in North Macedonia as 12 patients and two visiting relatives, authorities said Friday.

The fire broke out late Wednesday in the western town of Tetovo, destroying the facility within a few minutes. Twelve people were also injured. The blaze is believed to have started by accident, although an investigation is still under way. Witnesses and officials have said an explosion preceded the fire.

The public prosecutor's office said the dead were eight women and six men who ranged in age between 29 and 78.

The head of Tetovo’s COVID-19 center, Gzim Nuredini, said the fire spread very quickly.

“It all lasted three to five minutes,” Nuredini said, adding that medical staff and patients' relatives who were outside all tried to help extinguish the flames.

Prosecutors from Tetovo and the capital, Skopje were gathering video material from inside and around the hospital, and have hired an electrical engineering expert to help determine how the blaze broke out.

Medical staff and witnesses have also been questioned, and prosecutors have ordered the confiscation of all documentation on the construction of the facility to check for potential omissions.

Fires in COVID-19 hospitals or wards have cost dozens of lives in other countries, including Iraq and Romania

Nineteen field hospitals, funded by a World Bank loan, have been set up across North Macedonia over the past year to tackle surging coronavirus hospitalizations and a shortage of hospital beds. Health Minister Venko Filipce has said all 19 were constructed according to the specifications and standards laid out by the World Bank as a condition for the loan.

North Macedonia has said it is accepting an offer from other NATO allies to send fire experts. The government announced that a team from Germany s Federal Criminal Police Office will join the investigation.

President Stevo Pendarovski has said the investigation would be completed within five days, and that indications are the fire was not set deliberately.

North Macedonia’s government has declared three days of mourning from Thursday.