Ahmad, 50, watched flames engulf his friends at a drug rehabilitation centre in Kabul where he was undergoing treatment, unable to save them as they cried for help after a Pakistani air strike, leaving a scene he said resembled "doomsday".
The Afghan Taliban government says at least 400 people were killed and 250 injured in the Monday night attack. Islamabad denied having targeted any such facility, saying it had struck military installations and "terrorist support infrastructure".
Ahmad, who also volunteered as a guard at the hospital and gave only one name, said he and his 25 roommates had gathered in their dormitory after prayers when the attack occurred. He was the only survivor among them.
"The whole place caught fire. It was like doomsday," he said.
Health authorities said there were around 3,000 patients from across Afghanistan at the clinic at the time of the strikes, which triggered panic in Kabul, just after residents had broken their daily Ramadan fast.
People ran for cover as anti-aircraft guns fired from 9pm (1630 GMT).
"I heard the sound of the jet patrolling," Omid Stanikzai, 31, a security guard at the drug treatment centre, told AFP.
"There were military units all around us. When these military units fired on the jet, the jet dropped bombs and a fire broke out."
Mohammad Mian, who works in the radiology department of the hospital, said many young people under treatment lived in large containers on the campus and very few survived the strike.
Read morePakistan air strikes hit Kabul and Afghan border provinces, killing several
"It was extremely terrifying," he said. "Those who survived were the ones whose rooms were not destroyed and were fortunate. But the places where the bombs were dropped, everyone there was killed."
Blackened walls, bodies beneath the rubble
Afghanistan's vast poppy fields have long made it a major producer of opium, and millions of Afghans have struggled with addiction over decades of war and economic hardship.
The Taliban government banned all narcotics in 2023, including opium poppy cultivation, leading to an estimated 95 percent drop in opium production. Under the Taliban's crackdown, thousands of people struggling with drug addiction have been sent to the country's underfunded and overcrowded treatment centres.
When Reuters visited the site on Tuesday, the blackened walls on a single-storey building served as evidence of the fires that had raged inside only hours ago.
In other places, structures were reduced to piles of brick, metal and wood, with personal belongings of patients, including pillows, shoes, and items of clothing, left scattered among the debris.
In Ahmad's dormitory, some bunk beds still stood intact against a wall, their bedding undisturbed as the room, with the ceiling thrown off, lay open to the blue sky.
Crowds gathered outside the centre in the hope of hearing news of their loved ones.
AFP reporters counted at least 30 bodies being removed from the rubble of the facility and saw medics treating dozens of wounded in the chaotic and smouldering aftermath of the attack.
Baryalai Amiri, a 38-year-old mechanic, came to the site where his brother was admitted about 25 days ago.
"We are not given the proper information," he told AFP, as rescuers picked through the rubble nearby. "So far, we don't know where he is."
Dr Ahmad Wali Yousafzai, a health officer at the hospital, recalled three explosions whose blasts he said hurled some of his colleagues from one wall to another.
As fires erupted, there were screams and cries for help "from all directions", he said.
"We were too few in number to save all of them," he added.
Ambulance driver Haji Fahim was among those who transported bodies to the Afghan-Japan hospital close by, moving at least eight bodies over five hours.
"Now we have come again ... there are still bodies under the rubble," he said on Tuesday.
(FRANCE 24 with Reuters and AFP)