About half of them were children and adolescents and 80 percent were Syrian nationals, according to UNHCR.
More than 30,000 people, mainly Syrians, have crossed into Syria from Lebanon in the past 72 hours, according to the United Nations refugee agency (UNHCR).
The escalating conflict between Israeli forces and Hezbollah has displaced more than 90,000 people since September 23, the agency said on Friday.
About 80 percent of those crossing over are Syrians and about 20 percent are Lebanese, said Gonzalo Vargas Llosa, the UNHCR representative in Syria.
“They are crossing from a country at war to one that has faced a crisis conflict for 13 years,” an extremely difficult choice, he told a news conference.
Lebanon is home to about 1.5 million Syrians who fled civil war in their country.
Israel has dismissed global calls for a ceasefire with Hezbollah and continues a bombing campaign that has killed more than 700 people in Lebanon since Monday.
Nine members of one family from Shebaa, including four children, were the latest victims.
More than 5,000 people have been injured, according to the latest figures from Lebanon’s Ministry of Public Health.
Health Minister Firass Abiad said 25 people have been killed since Friday morning in Israeli strikes on Lebanon.
Israel’s Defence Minister Yoav Gallant reiterated that the military would keep targeting Hezbollah until northern Israel is safe again.
“We are hitting Hezbollah very hard over the past year and in particular over the past few weeks,” he said during a visit to the northern town of Safad, according to The Times of Israel newspaper.
Vargas Llosa said half of those crossing into Syria are children and adolescents, adding that men are making the crossing in smaller numbers than women.
“We will have to see over the next few days how many more do so,” he added.
UNHCR chief Filippo Grandi said this week that the mass displacement in Lebanon was “yet another ordeal for families who had fled years of civil war in Syria … only now to be bombed in the country where they sought shelter”.
“The Middle East cannot afford a new displacement crisis. Let us not create one by forcing more people to abandon their homes,” he said.