A flash flood struck a group of 25 teenagers hiking in Israel’s southern desert Thursday, sweeping 10 of them to their deaths as an unseasonal storm hit the region, Israeli police said in a statement.

Nine of the teenagers’ bodies were recovered, officials said, after torrential rains swept over an area that is usually arid and dry. Volunteers, together with police and military search-and-rescue teams, were still searching for the 10th youth as nightfall set in.

Israeli media outlets reported that among those killed were eight girls and one boy. They were members of a post-high-school, pre-military educational academy, part of a group of 25 teens who had set out for a hike Thursday afternoon in an area just south of the Dead Sea. The teen still missing is a female.

Television stations canceled scheduled broadcasts to air dramatic images from the rescue operation. The main question being asked was why the group had decided to continue with the hike in an area known for flash floods.

Warnings were issued Wednesday and Thursday by Israel’s Meteorological Service about the possibility of flash floods in the area, where even small amounts of rainfall can cause powerful flooding, the Haaretz newspaper reported. 

Prime Minister Benjamin Netanyahu called it a “disaster” and said he was being updated regularly by those conducting the search.

Israeli media outlets reported that police would be opening a probe into the tragedy to determine why the group had proceeded with their hike without the necessary permits and under such harsh conditions.

An exchange between one of the girls who was killed and a friend, showing her complaining about having to go on the hike in such weather, was published by Israel’s Hadashot news.

“We could end up dying there,” wrote the girl to her friend. It was not immediately reported which one of the dead girls sent the messages.

The heavy rains began Wednesday in the same area. Not far from where the youths were engulfed Thursday, a 17-year-old Bedouin Israeli was swept away in a similar flood.