Images taken by frightened families showed a fireball the size of a football field erupting high into the night sky. It wounded hundreds and left scores unaccounted for.
The separatist government said on Friday that forensic experts had been able to piece together “170 remains” of bodies that will be brought to Armenia for identification.
It added that 349 people – most of them suffering severe and critical burns – were in hospital.
Blast survivor Samvel Hambardzyumyan said he only escaped serious injury because there were others in front of him in the petrol queue.
“There were nine people ahead of me. If they hadn’t been there, I would have been burned alive,” the 61-year-old said.
Hambardzyumyan’s face was partially burned and his hands were wrapped in heavy bandages. “No one knows exactly what happened,” he said.
The updated toll means that nearly 600 people have died since Azerbaijan launched a 24-hour blitz that forced the rebels to agree to disarm last week.
The Azerbaijani offensive was the shortest and most decisive of any conflict the predominantly Christian Armenian and Muslim Azerbaijani rivals have waged since the region’s status became disputed with the collapse of the Soviet Union.
The separatists agreed on Thursday to dissolve their government and become a formal part of Azerbaijan by the end of the year.
The decision marked the end of one of the world’s longest and seemingly most intractable “frozen conflicts”, one that Azerbaijan was able to finally win while long-standing Armenian ally Russia was bogged down in its war on Ukraine.
It prompted an outpouring of grief in Armenia, immortalised in a viral clip of a Yerevan TV presenter breaking down in violent sobs while reading a separatist statement saying Nagorno-Karabakh will “cease to exist”.
Azerbaijan is now holding “reintegration” talks with separatist leaders while at the same time detaining some senior figures from its former government and military command.
On Wednesday it detained a businessman and philanthropist who headed the government for four months, and on Friday detained the deputy commander of the rebel force.
Both are officially suspected of “terrorist” activities.
Azerbaijan might end up taking over little more than empty homes and uncultivated fields by the time the separatist government hands over its remaining authorities to Baku.
Yerevan said 93,000 of the region’s estimated 120,000 people had fled since Azerbaijan unlocked the only road linking Nagorno-Karabakh with Armenia on Sunday.
The exodus has been accompanied by accounts of families burning their belongings so that they do not fall into Azerbaijani hands.
Refugee Angelina Agabekyan showed a video of her husband setting his uniform and military documents on fire before the family joined the flood of people taking Soviet-era Ladas and beat up vans out of Stepanakert.
Agabekyan’s little son joyfully added his toys to the flames “so that the Azerbaijanis don’t get to play with them”.
The episode highlights the deep mistrust and ancient ethnic feuds taring at a region that has changed rulers repeatedly over the centuries.
Nagorno-Karabakh is internationally recognised as part of Azerbaijan – a status it has enjoyed since first being handed to Baku by Moscow in the 1920s.
But it has been populated by ethnic Armenians since at least the 2nd century BC and is viewed as a cherished ancestral home by many Armenians.
The region’s supporters and pro-Russians staged six days of anti-government protests that they interrupted this week to help Prime Minister Nikol Pashinyan focus on helping the refugees.
But they intend to hold another big and disruptive rally on Saturday aimed at punishing Pashinyan for deciding not to help separatist forces fight Azerbaijan. Pashinyan has tried to deflect the blame on Russia.
Moscow has deployed peacekeepers in the region that were meant to police a truce ending a 2020 war in which Baku clawed back some of the lands it lost to the separatists in the 1990s.
Pashinyan called Yerevan’s current alliances “ineffective” and urged parliament in next week’s session to ratify a document that would make Armenia a member of the International Criminal Court.
The ICC has issued an international arrest warrant for Russian President Vladimir Putin.
The Kremlin said it would treat Armenia’s ICC membership as an “extremely hostile” step.