A rare storm dumped rain across Israel over Wednesday night and Thursday morning, causing flash floods and wreaking havoc in the south of the country.

The rains, which caused the Sea of Galilee to rise some 2.5 centimeters (1 inch), were the heaviest ever recorded for the month of May. The precipitation brought dry riverbeds to life, flooding low-lying areas, especially in the Judean Desert and Negev in the south of the country.

On Thursday morning schools near the Dead Sea were closed and several main roads in the area were blocked by authorities. The Eilat airport was temporarily closed due to flooding, and the Health Ministry issued a warning against swimming in the Mediterranean, citing pollutants in runoff making its way to the sea.

Several groups of hikers and tourists were stranded by the rain. At Masada, some 200 students and their parents were stranded for hours. The group, on a school trip, arrived at the historic site near the Dead Sea early Thursday, but the road was subsequently closed, forcing them to wait for hours in their buses.

On Thursday morning, rescue units used helicopters to evacuate 70 American tourists, members of a World Bnei Akiva group, from a camping site near the Nekarot stream in the Arava region, after they were trapped by a flash flood. Another group of tourists, some 100 hikers from the US and Germany, was rescued from the same region.

Route 90, the main highway running along the Dead Sea, was closed in some areas after flash floods covered the road. Three tour buses, carrying visitors from Thailand on their way from Jordan to Ein Gedi, were reported trapped on the road.

On Route 40 in the Negev, a driver was rescued by authorities Thursday morning after his vehicle was caught in a flash flood near the Paran river.

The driver was taken by helicopter to Yoseftal Hospital in Eilat.

Police urged citizens in the hard-hit Tamar Regional Council, near the Dead Sea, to stay indoors until further notice. Schools in the area were closed Thursday.

By Thursday morning the city of Arad had reported 44 millimeters of rain had fallen from the storm, 40 times the average for this time of year, according to the Israel Meteorological Service. Jerusalem saw 32 millimeters, Beersheba 24 millimeters and Ra’anana 45 millimeters. Tel Aviv saw 27 millimeters.

The IDF Spokesman’s office reported that due to weather conditions, US National Security Advisor Susan Rice, who is currently in Israel for a series of high-level talks between Jerusalem and Washington, was forced to cancel a planned trip to the Palmachim IAF base. The trip will be rescheduled for Friday, the report added.

The rains had tapered off by late Thursday, but a flash flood warning was to remain in effect until Friday afternoon.