An Israeli airstrike in south Lebanon on Sunday evening killed four civilians, including a woman and three children, raising the likelihood of a dangerous new escalation in the conflict on the Lebanon-Israel border.

Israeli troops and Hezbollah militants and their allies have been clashing for a month along the border since the start of the Israel-Hamas war. While clashes remain largely contained, they have increased in intensity as Israel conducts a ground incursion in Gaza against Hezbollah ally Hamas.

Lebanon’s state-run National News Agency reported that two civilian cars carrying members of the same family — one of them a local journalist — were driving between the towns of Ainata and Aitaroun on Sunday evening when they were hit by an Israeli airstrike. One of the cars was hit directly and burst into flames, the report said. One woman and three girls, ages 10, 12 and 14 were killed, and others were wounded, it said.

Shortly after the Israeli strike, Hezbollah said its fighters had fired Grad rockets from southern Lebanon into Israel in response. A number of rockets hit the northern Israeli town of Kiryat Shmona Sunday, Israeli rescue services said. Videos verified by The Associated Press showed a burning car on the street of Kiryat Shmona.

At least one civilian was killed Sunday as a result of attacks by Hezbollah, the Israeli military said, but it wasn't immediately clear if it was in the Kiyat Shmona attack or an earlier one.

Samir Ayoub, the Lebanese journalist, who was in the car in front of the one that was struck, told the AP that the three girls killed were his sister’s children and the woman was their grandmother.

“There were no men in the car that was hit — there were three innocent young children with their grandmother and their mother,” he said. “Three children were burned in the car and no one could save them. And I pulled out their mother as she was screaming, ‘My children!’ Where are the terrorists? Israelis, you are the terrorists."

Mohammad Suleiman, head of Salah Ghandour hospital in the town of Bint Jbeil, the bodies of the woman and three children were “completely burned." The children's mother was wounded but in stable condition and was transferred to another area hospital, he said.

Daniel Hagari, an Israeli military spokesperson, didn't comment on the details, but told reporters, “We study and investigate all incidents that take place to know the details.”

Lebanon’s caretaker prime minister, Najib Mikati, condemned Israel for the drone attack, calling it a “heinous crime.” He said that Lebanon will file a complaint to the U.N. Security Council.

Earlier Sunday, local Lebanese officials said an Israeli drone had struck near two ambulance on their way to pick up casualties from overnight strikes in southern Lebanon, wounding four paramedics. The Israeli army said in a statement that it had launched strikes on a “terrorist cell” that was attempting to fire missiles toward Israel from the Ras Naqoura area in south Lebanon and hadn't intentionally targeted the vehicles.

Also Sunday, Hezbollah said in a statement that it had targeted an Israeli military vehicle across the border from the Lebanese town of Blida with guided missiles Sunday, which it claimed had killed and wounded members of the crew.

The death of the woman and three children raised the number of civilians killed on the Lebanese side in the border clashes to at least 14, while at least two Israeli civilians have been killed, as well as seven Israeli soldiers and dozens of fighters with Hezbollah and allied groups in Lebanon.

Hezbollah officials have warned that if Israel kills Lebanese civilians, it will be considered a violation of the rules of engagement and it will retaliate by attacking civilian targets.