Jordanian warplanes struck targets in southern Syria after a shoot-out between its security forces and drug smugglers at the border on Monday.
Suwayda 24, a network of citizen journalists in southern Syria, said a woman and two children were killed in a strike on a sheep farm in Thibeem on Monday evening.
The town is in the southern province of Suweida, near the border with Jordan.
The three victims "were barely recognisable", according to medical staff at the Suweida National Hospital.
Reuters quoted regional intelligence sources as saying that the raids focused on the hideouts of drug smugglers supported by Iran, following a border shoot-out earlier on Monday.
The raids were carried out as Gen Charles Brown, the US chairman of the Joint Chiefs of Staff, visited Amman for a meeting with King Abdullah II.
They discussed "means to bolster defence and military co-operation", the Royal Palace said.
The US is the main sponsor of advanced monitoring and reconnaissance systems installed on the border with Syria in recent years.
Jordan's air force reportedly struck targets in southern Syria at least once this year, as drug shipments from areas under the control of the Syrian military and allied pro-Iranian militias continued despite a regional rapprochement with President Bashar Al Assad.
Another site struck on Monday in south Syria was the house of drug smuggler Shaker Shoueigher, but there were no casualties, Suwayda 24 said.
The Jordanian army said it killed several smugglers who tried to shoot their way past border forces on Monday and arrested nine.
An army statement said the shoot-out lasted 14 hours.
It quoted the head of the Jordanian Joint Chiefs of Staff, Maj Gen Youssef Al Hunaiti, who said that the military is "determined to pursue the armed groups" behind the drug smuggling.
Syria's border with Jordan has become an important route for the trafficking of narcotics after Mr Al Assad's military regained control of the area from rebels in 2018, following a deal between Russia, the US and Israel.
This was a major factor in Jordan's drive for a regional rapprochement with Damascus over the past two years.
The kingdom's efforts appear to have cooled in the second half of this year, with officials in Amman saying the drug smuggling remains a security threat.
The clashes on Monday occurred on Jordanian territory and led to the seizure of five million Captagon pills, 13,000 pouches of hashish, and weapons, the military said.
They follow an increase in attempts by drug smugglers to “cross the border by force, through the targeting of border guards” over the past two days, it added.
Attempts to smuggle narcotics into northern Jordan from areas under the control of the Syrian military and allied militias supported by Iran tend to increase in the winter, when the weather provides more cover, helping to circumvent US-supplied sensors and other anti-infiltration devices.
