BEIRUT — An explosion at a gas station outside Damascus on Wednesday turned a long line of cars waiting for rarely available fuel into a deadly inferno that killed at least 30 people, according to reports from witnesses who blamed the blast on a government airstrike.
The violence came as the United Nations released a study showing that nearly 60,000 people had been killed in Syria’s 22-month-old conflict, a number that is a third higher than estimates by antigovernment activist groups.
Also Wednesday, the family of James Foley —
A recent flurry of diplomatic activity by Russia, the United Nations’ special envoy, and others aimed at finding a political solution in Syria appeared to founder in recent days as neither Bashar Assad, the Syrian president, nor his opponents expressed a willingness to make concessions to end the conflict.
The explosion near Damascus took place in a heavily contested suburban area where scores of people had lined up at a gas station for fuel, which had just become available there after about a month, witnesses said. Videos from antigovernment activists showed charred and dismembered bodies.
One man thought that the regime had sent fuel to the station as a trap, then hit it with an airstrike.
One man, who gave only his nickname, Abu Fuad, for safety reasons, said in a telephone interview that he had just filled his gas tank and was driving away when he heard the screech of fighter jets.
He said he was less than a quarter-mile away when he heard the explosions.
‘‘There were many cars waiting their turn,’’ he said. ‘‘Yesterday, we heard that the government sent fuel to the gas station here, so all the people around came to fill up their cars.’’
In a sign of the depth of distrust the conflict has spawned, Abu Fuad suggested that restocking the station was a government ruse.
‘‘They sent fuel as a trap,’’ he said.
In the Damascus suburb of Moadhamiya, at least six people, most of them children from a single family, were killed when a mortar shell exploded, according to video and antigovernment activists. It was unclear who had fired the shell.
In northern Syria, rebels used rockets to attack the Taftanaz military airport, a long-contested area in the province of Idlib, activists reported. Rebels have also stepped up attacks on airports in the neighboring province of Aleppo, trying to disrupt the warplanes and helicopters that government forces increasingly use for attacks in the north.
The UN study suggested the war’s toll was far greater than previously estimated. Two days ago, the Syrian Observatory for Human Rights, a UK-based rebel group that tracks the war, reported 45,000 deaths, mostly civilian, since the conflict began in March 2011.
‘‘The number of casualties is much higher than we expected and is truly shocking,’’ the UN high commissioner for human rights, Navi Pillay, said in a statement after her agency released the study.
“We must not compound the existing disaster by failing to prepare for the inevitable — and very dangerous — instability that will occur when the conflict ends,’’ she added.
To avoid repeating the experience of collapsed states like Afghanistan, Iraq, and Somalia, she said, ‘‘serious planning needs to get underway immediately, not just to provide humanitarian aid to all those who need it, but to protect all Syrian citizens from extrajudicial reprisals and acts of revenge.’’
The study’s surprisingly high death toll reflected only those killings in which victims had been identified by their full name, and the date and location of their death had been recorded, leaving the possibility of many more dead.
Independent researchers compiled reports of more than 147,000 killings in Syria’s conflict from seven sources, including the government. When duplicates were removed, there remained a list of 59,648 people killed between March 2011 and the end of November.