At least 70 people have been killed in northern Afghanistan after a Nato aerial raid on two hijacked petrol lorries.
The assault was carried out in Kunduz province, with some witnesses putting the number of dead and injured as high as 130.
Nato has admitted that Friday's attack had possibly killed civilians.
Anders Fogh Rasmussen, the Nato secretary-general, said: "Certainly, a number of Taliban were killed and there is a possibility of civilian casualties as well."
A spokesman for the White House said that the US would investigate the raid.
"Obviously, any time there is loss of life in a conflict like this, particularly the civilian loss of life, it's something we've expressed in the past and continue to express great concern about," Robert Gibbs said.
Hijacked tankers
James Bays, Al Jazeera's correspondent near Kunduz city, said: "I've been to the village nearest to where the bombing took place. A very sad scene there. Watching the bodies being brought outside the mosque in the village, people praying. Real shock and anger at what had happened."
Bays said that members of the Taliban had hijacked the fuel tankers, travelling from Tajikistan, but that they had become mired in mud.
"Some in the village are saying the Taliban asked locals to come and help because these trucks were stuck, and it seems that is when the air strike was launched," he reported.
Local villagers had also been offered fuel from the vehicles and were siphoning it off when Nato aircraft struck.
"The key question will be exactly why Nato decided to launch this air strike. What evidence did they have, what rules of engagement were they operating under?"
Moin Marastial, who represents Kunduz province in the Afghan parliament, told Al Jazeera: "More than 100 people had been killed, according to local sources.
"We don't know how many people died exactly because the bodies of Taliban and locals were taken away after midnight, but it is definitely more than 120 people in the area.
"Nato is promising to Afghanistan that they will use air strikes when they are fighting the Taliban, but they are not doing that. Still we are losing a lot of civilians because they don't know the area properly."
'Civilians killed'
Mohammad Omar, the Kunduz governor, said that at least one senior Taliban commander and four Chechens was among the dead.
Zabihullah Mujahid, a Taliban spokesman, said that as many as 90 civilians, who had come out to take fuel from the lorries, had been killed.
He confirmed that the two lorries had been hijacked, but said that only one was hit in the air raid after the other got stuck in the mud in Aliabad district and was abandoned.
An Al Jazeera producer in Kunduz province said that he had seen at least 50 injured people in a local hospital, all burns patients, and all of them said they had lost family members in the incident.
One villager outside the hospital said: "My brother was burnt when the aircraft bombed the fuel tankers. I don't know whether he is dead or alive."
Our correspondent said: "If these reports are confirmed, this will be a definite blow to General [Stanley] McChrystal, the US and Nato army commander in Afghanistan, who has urged US forces to avoid civilian causalities where at all possible."