Police in Santa Maria, Brazil, have allowed some witnesses of a deadly nightclub fire back into the club to assist officers investigating the circumstances of Sunday's blaze that killed 235 people.
After surveying the area Wednesday, police confirmed that the fire originated in an area where pyrotechnics were used.
Survivors say a band member shot fireworks toward the ceiling, triggering the blaze that engulfed the building. Police say there was no emergency lighting, the only fire extinguisher available was not working, and the only exit was partially blocked.
The club was packed with people when the fire broke out. Many who tried to flee were overcome by smoke inhalation or were trampled while trying to find the exit.
More than 100 other people were injured. Medical officials say dozens of them remain in critical condition.
A makeshift memorial has formed outside the club in remembrance of the victims. Police have arrested two club owners and two members of the band.
Police say one of the club owners tried unsuccessfully to hang himself this week while in custody.