The tragedy unfolded at the Colectiv venue in Bucharest on Friday (30Oct15) when fire broke out as Goodbye to Gravity performed a concert to launch their new album.

The blaze quickly spread and left 31 revellers dead - including two members of the band - and at least 180 injured, including frontman Galut.

Onlookers who survived the horror have now revealed how Galut initially joked about the incident before he realised it was turning serious. In a grisly twist, the band had earlier performed a new song called This is the Day We Die.

In a post on Facebook.com, rock fan Delia Tugui, who was at the gig with her husband and son, recalled the moment a spark on stage apparently ignited a piece of polystyrene decoration.

She wrote, "The lead singer made a quick joke: 'This wasn't part of the program.' The next second, he realized it wasn't a joke and asked for a fire extinguisher. In 30 seconds... the fire spread all over the ceiling. People rushed to the entrance but it was too narrow, and people panicked. Friends were looking for each other under the pile of people. It was a nightmare."

Galut and an unnamed bandmate are receiving treatment for extensive burns at a hospital in Bucharest, but two other members of the group - guitarists Vlad Telea and Mihai Alexandru - perished in the inferno. A fifth rocker, bassist Alex Pascu, reportedly underwent emergency surgery for his injuries.

Police are investigating the cause of the blaze, which is the deadliest nightclub fire in the country's history, and have arrested three owners of the Colectiv venue.