A stream of refugees fleeing Lebanon to Syria crossed a narrow makeshift bridge on foot Sunday in the Qusair area of Syria’s Homs province after the official border crossing was put out of commission by an Israeli strike two days earlier.

Only three functioning crossings remain between the countries, which share a border 375 kilometers (233 mi) long.

In late September, an Israeli airstrike hit the border crossing of Matraba in Lebanon’s northeast, forcing it to close. A few weeks later came a strike on Masnaa, the main crossing between the two countries, putting it out of service. The Jousieh crossing was struck on Friday.

The Israeli military has accused the Hezbollah militant group of using the crossings to move weapons and military equipment from Syria to Lebanon. But humanitarian officials say that the closure of the crossings have intensified an already severe humanitarian crisis by blocking key routes for supplies and impeding access for those fleeing to safety.

“The situation is a tragedy,” said Ghossoun Mubarak, who fled with her three children from the city of Baalbek in eastern Lebanon, describing the bombardment that pushed her to leave her home. They crossed via the makeshift foot bridge on Sunday.

The United Nations refugee agency, or UNHCR, said this week that around 430,000 people had crossed from Lebanon into Syria over the past month since Israel launched a major aerial bombardment and ground invasion of Lebanon as part of its push against Hezbollah. Lebanese officials give a higher estimate of more than half a million people.

Rula Amin, a spokesperson for the UN refugee agency, UNHCR, voiced concern over the damage to the crossings, calling them “a main lifeline for people escaping the conflict.”

“Today, it was better,” said Omar Abu Jabal, 29, who was returning to Lebanon Sunday via the Jousieh crossing after a work trip. “No issues along the way. But before, there were bombings, which stopped people from moving.”

Nabil Aakoul, director of transportation for the Homs province, said the recent strikes destroyed a bridge over the Orontes River, disrupting movement between vital agricultural areas. Aakoul estimated that rebuilding the bridge will cost around 35 billion Syrian pounds (around $2.5 million dollars at the official exchange rate), while the damage has severed access to agricultural areas and isolated communities dependent on cross-river trade and travel.

Yahya Abu Youssef, who lives near the damaged bridge, described the strike as “inhumane” and reported injuries to children and livestock nearby. “All that’s here is a bridge connecting villages and farms,” he said, noting that villagers now face an additional 10 kilometers (6 miles) of travel to reach the city of Homs.