An air strike on a convoy carrying fuel across the Iraqi border into Syria killed at least 10 people late Tuesday, members of paramilitary groups operating in the area said, according to The Associated Press.

The strike hit a convoy of about 15 trucks that had crossed from Iraq into Syria near Al-Qaim, two paramilitary officials told the news agency.

It was not immediately clear who carried out the attack. It also was not immediately clear where the convoy was coming from, but the paramilitary officials said some of those killed were Iranian.

CENTCOM denied the US was responsible for the deadly strike.

Tensions have been mounting in Iraq in recent months, with drone attacks repeatedly targeting the city of Erbil.

In June, a drone exploded in the city, injuring three people and damaging several cars.

In March, Iran attacked Iraq’s northern city of Erbil with a dozen ballistic missiles.

The Saudi channel Al-Hadath reported at the time that the missiles were fired in retaliation for the killing of two officers from the Revolutionary Guards in an air strike in Syria which was attributed to Israel.

In September, Iranian drones targeted an Iranian-Kurdish opposition group in northern Iraq, killing at least nine people and wounding 32 others. A day later, Iraq summoned the Iranian ambassador to deliver a diplomatic complaint.

Tuesday’s air strike came a day after a US citizen, 45-year-old Stephen Edward Troell, was fatally shot in central Baghdad.

Troell, a native of Tennessee, was killed by unknown assailants in his car as he pulled up to the street where he lived with his family in Baghdad's central Karrada district. It was a rare killing of a foreigner in Iraq in recent years, as security conditions have improved, according to AP.

No group claimed responsibility for Troell's killing. Prime Minister Mohammed Shia al-Sudani, less than two weeks in office, ordered an investigation.