The death toll has risen to 29 and about 146 remain hospitalized after a blaze broke out late Friday at an old factory being used as a club.
Forensic experts, meanwhile, began the first autopsies of victims on Sunday.
Hundreds of young people were packed into a factory in central Bucharest, Romania, which was being used as a music club on Halloween eve.
A band was celebrating a new album with a free concert when suddenly the 300 or 400 people were scrambling toward the only exit.
The club is called Colectiv, built inside a Communist-era factory.
Witnesses say pyrotechnics sparked a fire that quickly became a widespread blaze with dark, blinding smoke.
A spokeswoman for the Interior Ministry said many of the injured — who were taken to 12 area hospitals — were in critical condition suffering from burns and smoke inhalation.
A prosecutor and fire specialists will investigate the scene and determine how the fire started, she said.
Romania’s Prime Minister, Victor Ponta, cut short a visit to Mexico to return to Bucharest and has decreed three days of mourning. Romanian President Klaus Iohannis said he was “shocked and deeply saddened” by the news.
The fire appears to be the deadliest nightclub blaze since a 2013 fire at a nightclub in Santa Maria, Brazil, killed 235 people.