A blaze that killed at least 35 girls at a shelter for troubled youths erupted when some of them set fire to mattresses to protest rapes and other mistreatment at the badly overcrowded institution, the parent of one victim said.

Officials said they are still investigating who started the fire Wednesday at the long-criticized shelter on the outskirts of Guatemala's capital. It houses troubled and abused boys and girls as well as juvenile offenders.

Nineteen victims were found dead at the scene, and 16 more succumbed one by one to their grisly injuries at hospitals in Guatemala City. Several more girls were fighting for their lives, some with severe burns over more than half their bodies. The National Institute of Forensic Science said that 17 of the bodies have been identified.

The 35th death was announced by the General Hospital late Thursday while President Jimmy Morales called for a restructuring of the country's youth shelter system, which houses some 1,500 children around the country, during a news conference.

Outside the presidential palace, dozens of protesters gathered to demand answers.

The fire started when someone ignited mattresses in a dormitory that held girls who had been caught the day before during a mass breakout attempt, authorities said.

On Thursday, distraught parents haunted hospitals and the morgue, passing scraps of paper scrawled with the names of loved ones they hoped to find.

Geovany Castillo said his 15-year-old daughter Kimberly suffered burns on her face, arms and hands but survived. She was in a locked area where girls who took part in the escape attempt had been placed, he said.

"My daughter said the area was locked and that several girls broke down a door, and she survived because she put a wet sheet over herself," Castillo said.

"She said the girls themselves set the fire," he said, adding: "She said the girls told her that they had been raped and in protest they escaped, and that later, to protest, to get attention, they set fire to the mattresses."

Another surviving 15-year-old girl said that male residents had apparently been able to enter at least some of the girls' dormitories before the fire. She and others took refuge on a roof for fear of being attacked and saw the fire break out in a nearby building.

"I saw the smoke in the place," she said. "It smelled like flesh."

The state-run Virgin of the Assumption Safe House has long been the subject of complaints about abuse, inadequate food and crowded and unsanitary conditions behind its 30-foot wall. The shelter was built to hold 500 young residents but housed at least 800 at the time of the fire.