OUTSIDE BAGHOUZ, Syria -- Small trucks carrying disheveled men, women and children left the Islamic State group's last pocket of territory in eastern Syria in an escorted convoy on Friday, hours after U.S.-led coalition airstrikes meant to pressure the militants targeted the area on the banks of the Euphrates River.

At least 36 trucks and two buses were seen carrying civilians through a humanitarian corridor from the militants' last patch of territory in the remote village of Baghouz near the Iraqi border. They were escorted by gun-mounted pick-up trucks belonging to the U.S.-backed fighters who have delayed their final assault on remaining militants, pending the exit of civilians.

As the evacuation was taking place, automatic machine-gun fire could be heard in the distance and coalition aircraft flew overhead.

From a self-proclaimed "caliphate" straddling large parts of Syria and neighbouring Iraq that they seized in 2014, the militants have lost all but a tiny speck in Baghouz. Some 300 IS militants, along with hundreds of civilians believed to be mostly their families, have been under siege for more than a week in a tent encampment in the village.

A spokesman for the U.S.-backed force known as the Syrian Democratic Forces, Mustafa Bali, said there were coalition airstrikes and intermittent clashes earlier Friday with the militants, meant to pressure them into allowing the last civilians to leave.

"For this evacuation to be a success, there (needs to be) military action," Bali added.

The presence of so many civilians in Baghouz -- and possibly senior members of the militant group -- has surprised the SDF and slowed down the expected announcement of the extremist group's territorial defeat.

In the past few weeks, nearly 20,000 people had left Baghouz through the humanitarian corridor, leaving the IS holdout on foot, but the militants then closed the passage and no civilians left for a week until Wednesday, when a large group was evacuated. The displacement has overwhelmed camps in northern Syria hosting them, and at least 60 people previously evacuated from the militants' shrinking territory have died of malnutrition or exhaustion.

Bali suggested many civilians were still inside, in caves and tunnels under the tents as well as surrounding homes and buildings.

On the convoy that left Baghouz on Friday, civilians could be seen sitting atop the flatbed trucks, including women, covered from head to toe in black. One of them raised her index finger to the sky -- a gesture some Muslims make to say there is only one God, but also used to refer to the Islamic State group. Children's faces were caked with dust and dirt. Men mostly covered their faces with checkered scarves, looking away.

A boy, who appeared to be about 9 or 10 years old, pleaded to get out of the truck, saying he had stomach problems. The convoy stopped to let him out into the desert briefly.

Asked by an Associated Press team what the situation was like inside the village, he replied: "Not good."

He said he doesn't remember how long he has been in Baghouz, saying only "since a long time." He said he was from the city of Raqqa, farther to the north, which used to be the de facto capital of the so-called IS "caliphate."

Recapturing Baghouz would mark an end to the territorial rule of the militants' self-proclaimed caliphate that once stretched across a third of both Syria and Iraq. It would also allow President Donald Trump to begin withdrawing American troops from northern Syria, as he has pledged to do, opening a new chapter in Syria's eight-year civil war.

Few believe, however, that ending the group's territorial rule will end the threat posed by an organization that still stages and inspires attacks through sleeper cells in both Syria and Iraq. In the latest such attacks, IS claimed responsibility for a suicide car bombing that killed at least 15 people Friday, many of them oil workers, near the al-Omar oil field which now serves as a base for SDF troops and journalists covering the battle for Baghouz.

The Trump administration, which abruptly announced in December that it was pulling out of Syria, said Thursday that it will keep 200 U.S. troops in the country for now.

"A small peace keeping group of about 200 will remain in Syria for period of time," White House press secretary Sarah Sanders said in a one-sentence statement.