Militants in northern Iraq have massacred at least 80 men from the Yazidi faith in a village and abducted women and children, reports say.
Senior Kurdish official Hoshyar Zebari said the men were killed in two groups after a column of Islamic State (IS) vehicles arrived in Kawju on Friday.
A US drone strike later destroyed two vehicles from the convoy, he said.
Reports say US warplanes have struck IS positions near the Mosul dam, captured last week.
Residents near the dam told AP news agency that the air strikes hit on Saturday afternoon, killing some militants.
Kurdish regional Rudaw TV earlier said several surrounding towns were also struck.
An official from US Central Command would not confirm or deny the reports.
"For the safety and security of our personnel, we will not discuss or speculate on reports of ongoing or future operations," the official told the BBC.
The dam controls the water and power supply to a large area of northern Iraq.
'Convert or die'
Before carrying out the massacre in Kawju village, IS fighters reportedly told men to convert to Islam or die.
Mr Zebari, until recently Iraq's foreign minister, confirmed the attack after it was reported by Yazidi activists based in Washington.
He told the BBC that a US drone strike was directed at two of the vehicles near the village of Salhieh.
The US military confirmed the destruction by drones of two vehicles identified as belonging to IS near Sinjar on Friday morning, after receiving reports from Kurdish forces that the militants were attacking civilians.
Mr Zebari added that Kawju and other Yazidi villages had been reassured by nearby Sunni Muslim villages that they would protect them from harm, but were unable to keep those assurances when IS decided to attack.
The killings took place over the space of an hour, said a Yazidi MP, Mahama Khalil, who reportedly spoke to survivors.
A resident of a nearby village said an IS fighter from the same area had given him details of the bloodshed.
"He told me that the Islamic State had spent five days trying to persuade villagers to convert to Islam and that a long lecture was delivered about the subject today," said the villager.
"He then said the men were gathered and shot dead. The women and girls were probably taken to [the city of] Tal Afar because that is where the foreign fighters are."
Hadi Pir, a Yazidi activist and member of the Yazidi Crisis Management Team in the US, also said a deadline to convert had been given to the villagers.
The villagers were assembled at Kocho's only school, after which the men were shot, the activists said. Remaining villagers were then put on buses for an unknown destination.
IS-led violence has driven an estimated 1.2 million Iraqis from their homes. Whole communities of Yazidis and Christians have been forced to flee in the north, along with Shia Iraqis, whom IS do not regard as true Muslims.
Separately, fighting flared up on Friday in the mainly Sunni Anbar province, west of Baghdad, parts of which have been under IS control.
Some leaders of Iraq's Sunni Muslim minority have said they may work against the militants in cooperation with Iraq's new Prime Minister, Minister Haider al-Abadi, who is tasked with restoring order.
The mainly Shia Muslim government is locked in a fight with IS since the group led an insurrection in the north this summer, making the city of Mosul the capital of a self-declared state which extends into Syria.
Yazidi and Christian people in northern Iraq have faced persecution by the jihadists, prompting US-led air strikes and aid drops and calls for other Western states to arm opponents of IS.
In New York, the UN Security Council imposed sanctions on IS members.
It made six people associated with IS or the Syria-based Nusra Front subject to an international travel ban, asset freeze and arms embargo.
Backers of the two groups may also face sanctions.
UK ambassador at the UN Sir Mark Lyall Grant says the impact of this will only be felt in the long term.
"We're not suggesting that this resolution is going to immediately dramatically change the situation on the ground, " he said.
"But it is a first step towards establishing a longer term international framework for tackling this major threat."
At an emergency EU meeting in Brussels on Friday, the 28 member-states were left to decide individually whether they would arm Iraq's Kurds, the main opponent of IS in the north.
The UK said it would "consider favourably" any request to send arms to the Kurds, while the Czech government said it would be in a position to start deliveries of munitions by the end of the month.
Germany is legally prevented from arming countries involved in conflict, but Foreign Minister Frank-Walter Steinmeier, who is currently in Iraq, said he would go to the limit of "what is legally and politically possible" to help the Kurds.
Reproduced under licence from BBC News © 2014 BBC