Story highlights

Witnesses say the fire started quickly, there was heavy smoke

Spokeswoman for the Interior Ministry says many injured are in critical condition

At least 27 people were killed at the Colectiv nightclub, where a heavy metal band was playing

CNN  — 

Hundreds of young people were packed into a music club in central Bucharest, Romania, jamming to the head-pounding heavy metal music filling their ears.

It was almost Halloween at Colectiv, a trendy club built in the basement of a communist-era factory. The band, Goodbye to Gravity, was celebrating a new album with a free concert.

The blaze left the 300 or 400 people packed inside scrambling toward the lone exit in one of Romania’s deadliest fires in recent memory.

Authorities said the cause of the fire hasn’t been determined.

At least 27 people died and 162 were injured when the blaze broke out late Friday, authorities said.

A spokeswoman for the Interior Ministry, Monica Dajbog said many of the injured – who were taken to 12 hospitals – were in critical condition.

A prosecutor and fire specialists will investigate the scene and determine how the fire started, she said.

Goodbye to Gravity was having an album release concert, the group said on its social media pages.

Paul Angelescu, a reporter with ProTV, said the mayor told him the club had all the necessary permits to operate as a club.

Romanian President Klaus Iohannis said he was “shocked and deeply saddened” by the news.

“It is a very sad moment for all of us, for our nation and for me personally,” he said in a post to his Facebook page.

The fire appears to be the deadliest nightclub blaze since a 2013 fire at a nightclub in Santa Maria, Brazil, killed more than 230 people.

CNN’s Hamdi Alkhshali contributed to this report.