As the flames engulfed the room where Luis Huaman was trapped inside a warehouse in Peru's capital, he made a call to his mother in a desperate plea for help.
Nearly a day later, the fire was still raging and there was no sign of the 19-year-old.
At least four people were missing Friday after a warehouse filled with tons of combustibles caught fire. Relatives of two men trapped in the blaze said both were locked inside the rooms where they were working when the fire broke out. Cellphone video obtained by a local television channel showed another now missing man desperately kicking a door in a futile bid to escape.
"They locked them in, which is criminal,'' President Pedro Pablo Kuczynski said as he covered his mouth with a paper mask to protect himself from the fumes. "They were practically slave workers.''
The fire cast a critical light on Peru's little regulated and vast informal employment sector, which encompasses as much as 70 percent of the nation's workforce.
"Peru doesn't have enough labor inspectors for the thousands of businesses that exist and for the other enormous number that operate off the books,'' said Kardy Villavicencio, a lawyer and labor rights expert.
The fire broke out Thursday afternoon and leaden clouds of smoke continued to fill the air just 15 blocks from Peru's presidential palace 20 hours later.
Temperatures inside the building reached up to 800 degrees Celsius (1,472 Fahrenheit), firefighter commander Fernando Campos said. Firefighters said it was likely the worst blaze they had encountered since a 2001 fire that killed 277 people.
Police said they had been unable to locate the building's owner.
Cesar Herrera said his 21-year-old nephew, Jovi Herrera, was one of those missing. He said his nephew had phoned begging for help to find the key to the room he was locked in.
"Help me, I'm going to die,'' Herrera quoted the young man as pleading.
Bertha Villalobos, the mother of Huaman, said she also got a frantic call from her son telling her he was stuck in a locked room. She said he had told her previously about being locked in while working, and she always made him food to take, knowing he would be stuck inside.
"My son told me the owner would lock them in,'' she said.