Mahrous al-Tukhie was sleeping when poison rained down from the sky. Within hours, 34 members of his family has been killed by the lethal vapors.
The 46-year-old says he was woken up by a loud bang at 2 a.m. Then he felt "something" in his chest.
"I realized it must be some kind of chemical," Tukhie said.
Three years ago this week, the former construction worker lost his wife, two daughters and a son when rockets packed with the deadly nerve agent sarin exploded near their home in East Ghouta. Thirty members of Tukhie's extended family also died in the attack on their rebel-held Damascus suburb, widely believed to have been carried out by forces loyal to Syrian President Bashar al-Assad.
The Syrian government has blamed the attack on foreign fighters and their supporters.
Tukhie's loved ones were among what the U.S. estimates were some 1,429 people — including 429 children — who died in the Aug. 21, 2013 incident.
The events of that devastating night are still fresh to Tukhie, even three years later.
"I sat up and suddenly I couldn't breathe," Tukhie told NBC News of the initial moments. His littlest, Muhammad, rushed to his side: he was having trouble breathing.
Tukie wrapped a wet towel around his face and carried the 5-year-old onto the rooftop of his building. Then he went back for son Adnan, 10; daughters Salma and Ruba, 9 and 7; and his wife Haifa.
"I can't explain how I felt that moment, when I saw my children on the floor and my wife was suffering," he said. "They were dying in front of me."
Haifa was the first to go, he said, followed by the three older children.
Tukhie carried their bodies onto the street, where he quickly realized that his family was not alone in its suffering.
"Wherever I walked I saw dead bodies," he said. "People were screaming and covering their faces … Death was everywhere."
The attack sparked an international outcry but little action — despite President Barack Obama's declaration a year earlier that Assad's use of chemical weapons would be crossing a "red line."
Assad, though, agreed to handover Syria's entire chemical arsenal to be destroyed after the attack and a foreign military intervention was averted.
Muhammad Jaradah was one of the doctors who treated victims of the sarin attack and has kept close track of survivors. Many still suffer from respiratory diseases and psychological trauma, the heart specialist said.
While Assad has handed over his chemical stockpile, Jaradah said he and other doctors are still seeing the effects of different types of chemical attacks.
"Still to this moment chlorine attacks are taking place," Jaradah said. "The last one in our area was a month ago on the front lines of Jober and Harasta — we got 30 patients and three of them died."
Although chlorine gas is classified as a choking agent, it was not on the list of chemicals the Assad regime submitted to be destroyed.
On Wednesday, an international team concluded that both the Syrian government and ISIS have carried out chemical attacks since 2014. The group from the U.N. and the chemical weapons watchdog blamed the government for using chlorine gas in two attacks and ISIS fighters for using mustard gas in one attack.
'I remember my mom'
The surviving Tukhies today live in nearby Douma, another Damascus suburb surrounded by Syrian government troops. There is very little food, clean water and medicine.
Muhammad Tukhie suffers from constant breathing problems and frequently wakes up at night screaming, his father said.
An airstrike hit their house in September, badly injuring one of Mahrous Tukhie's legs. Now he walks with a crutch and cannot work, so is forced to rely on donations and handouts from his neighbors. The airstrike also destroyed his house along with all photos and other mementos of his family.
The surviving father and son do take solace from frequent visits the cemetery where the rest of their family is buried, offering prayers and remembering Haifa, Salma, Ruba and Adnan.
Muhammad said he missed playing with his older brother Adnan and going on picnics with the whole family.
"I remember my mom — she used to feed me and shower me," he said. "Now my dad does all that. May god keep him safe for me."