Jihadist supremo Abu Bakr al-Baghdadi, the world's most wanted man, was believed Sunday to have been killed in a US special operation in northwest Syria.
The elusive chief of the Islamic State group was thought to be dead after a US military raid in the Idlib region, US media reported early Sunday.
The White House announced President Donald Trump would make a "major statement" Sunday at 9:00 am (1300 GMT), without providing details.
Turkey said it had coordinated with the United States before the operation.
A war monitor said US helicopters dropped forces in an area of Idlib province where "groups linked to the Islamic State group" were present.
The helicopters targeted a home and a car outside the village of Barisha in Idlib province, said the Britain-based Syrian Observatory for Human Rights, which relies on a vast network of sources inside Syria for its information.
The operation killed nine people including an IS senior leader called Abu Yamaan as well as a child and two women, it said.
The war monitor could not confirm Baghdadi's death however and the jihadist organisation, which lost the last scrap of its once-sprawling "caliphate" earlier this year, did not immediately react on its usual social media channels.
An AFP correspondent outside Barisha saw a minibus scorched to cinders by the side of the road, and windows shattered in a neighbour's house surrounded by red agricultural land dotted with olive trees.
A resident in the area who gave his name as Abdel Hameed said he rushed to the place of the attack after he heard helicopters, gunfire and strikes in the night.
"The home had collapsed and next to it there was a destroyed tent and vehicle. There were two people killed inside" the car, he said.
- 'Joint intelligence'-
US media cited multiple government sources as saying Baghdadi may have killed himself with a suicide vest as US special operations forces descended.
He was the target of the secretly planned operation that was approved by Trump, officials said.
Turkey, which has been waging an offensive against the US-backed Syrian Democratic Forces (SDF) in northeast Syria in recent weeks, had "advance knowledge" about the raid, a senior Turkish official said.
"To the best of my knowledge, Abu Bakr al-Baghdadi arrived at this location 48 hours prior to the raid," the official told AFP.
The commander-in-chief of the SDF, who have been fighting IS in Syria, said the operation came after "joint intelligence work" with American forces.
From the outskirts of Barisha, an inhabitant of a camp for the displaced also heard helicopters followed by what he described as US-led coalition air strikes.
They "were flying very low, causing great panic among the people," Ahmed Hassawi told AFP by phone.
Another resident, who gave his name as Abu Ahmad and lives less than 100 metres away from the site of the destroyed house, said he heard voices "speaking a foreign language" during the raid.
The AFP correspondent said the area of the night-time operation had been cordoned off by Hayat Tahrir al-Sham, a group dominated by members of Syria's former Al-Qaeda affiliate controlling Idlib.
Between the trees, he glimpsed bulldozers at the site of the reported raid clearing out the rubble.
Long pursued by the US-led coalition against IS, Baghdadi has been erroneously reported dead several times in recent years.
Officials told ABC News that biometric work was under way to firm up the identification of those killed in the raid.
Trump earlier tweeted, without explaining, "Something very big has just happened!"
In 2014, IS overran large swathes of Syria and neighbouring Iraq and Baghdadi appeared in a video that summer announcing a "caliphate" in regions they controlled.
- $25 million reward -
At the height of IS rule, Baghdadi's group implemented its brutal version of Islamic law on millions. The group has been blamed for mass executions, and accused of carrying out war crimes.
But several offensives in both countries whittled down that land, backed by the air power of the US-led coalition.
In March, the SDF ousted the extremist group from its last patch of territory in eastern Syria, forcing IS to revert to an underground guerrilla modus operandi.
Baghdadi -- an Iraqi native believed to be around 48 years old -- was rarely seen.
After 2014 he disappeared from sight, only surfacing in a video in April with a wiry grey and red beard and an assault rifle at his side, as he encouraged followers to "take revenge" after the group's territorial defeat.
His reappearance was seen as a reassertion of his leadership of a group that -- despite its March defeat -- has spread from the Middle East to Asia and Africa and claimed several deadly attacks in Europe.
The US State Department had posted a $25 million reward for information on his whereabouts.
In September, the group released an audio message said to be from Baghdadi praising the operations of IS affiliates in other regions.
It also called on scattered IS fighters to regroup and try to free thousands of their comrades held in jails and camps by the SDF in northeastern Syria.