Police investigating a fire in a Pakistan factory that killed 289 people described scenes of panic as the flames took hold, after studying closed-circuit video footage from inside the building.
The blaze at the Ali Enterprises factory in Karachi started on the first floor and caused terror among workers in a matter of seconds, senior police official Niaz Khoso told AFP on Friday.
The only exit from the building was through a door with an electronic lock which failed when the fire disrupted the power supply, he said, leaving workers trapped at the mercy of the smoke and flames.
Investigators are studying a crucial two-minute section of footage captured by six closed-circuit cameras as the fire broke out on Tuesday evening.
"The fire basically erupted on the first floor, where a group of people were sorting out the finished material," Mr Khoso said.
"A large quantity of finished garments are piled on the floor and workers are calmly busy in their work."
Sparks are then seen coming from electricity cables, which he said were of poor quality and installed unusually low in the walls.
"At 18:56 the images of fire come on screen. Workers start running helter-skelter as everything gets murky with the smoke amid the sparks of fire," he said.
"At the same time, people on the rest of the building get sense of the fire and start running for safety and then probably cameras are destroyed one-by-one and the footage abruptly ends."
The tragedy has prompted anger in Pakistan over the dismal safety standards endured by industrial workers, who toil in dangerous working conditions for poor wages, often to produce goods for export to Western customers.
Ali Enterprises produced ready-to-wear clothes for companies in Europe and North America, though precisely which brands it supplied remains unclear.
Police have registered a murder case against the factory's owners, who handed themselves in to court on Friday to apply for a special type of pre-arrest bail.
"The fire is definitely accidental, but what is more important and criminal is that the owners had given no exits to the workers to get saved in case of emergency," Mr Khoso said.
"The only gate from where people come and go had electronic locking, which failed to open when fire disrupted the power supply."