A pool party on a hot day in the middle of summer is supposed to be fun. At one recent pool party in Karmei Yosef, Israel, that’s how it started but far from how it ended.

Friends gathered at a private home. Music played. Some guests were in the pool. Some guests sat on the edge of the pool with their feet dangling in the water. Other guests stayed on the pool deck.

Then something extremely unusual and quite terrifying happened. A sink hole opened under the pool and sucked everything in the pool inside. That included all the water, two party guests and all the pool floats. One party goer was able to climb out on his own, but another guest had to be rescued by firefighters. Unfortunately, he did not survive.

Aviv Bublil, the lifeguard who was at the party, testified about the incident. She explained, “There was a vortex inside the pool. Something that did not look normal, like taking out the cork or opening the drainage pit. Strange waves formed, all the water was pumped down, at first I did not see Where are they being drawn from.”

Bublil knew something unusual was happening, and she “screamed” at everyone to get out of the pool, but they didn’t understand at first and “thought it was some kind of game.” She claims there were six people in the pool at the time.

Bublil explained that the water drained out of the pool “in a matter of seconds. It’s not something that looks normal, that’s why I realized it’s some kind of unusual event I don’t usually see in pools.”

She added that when she saw two people get sucked into the sinkhole, she wanted to jump in and try to rescue them, but other people at the party stopped her. It didn’t take long for her to understand that she wouldn’t be able to get to them.

A video of the pool’s collapse was shared on Twitter and has now been viewed well over a million times. You can see it for yourself below.

According to Professor Shmuel Marco, from the Department of Geophysics at Tel Aviv University the pool most likely collapsed due to “a human rather than geological phenomenon.” Marco explained, “They do exist in the Dead Sea area, where there is a thick layer of salt below the surface a few meters deep, and when fresh water seeps in they dissolve the salt below the surface and an underground space is created and the surface collapses inside.” The sinkhole was likely caused by “water infiltration.”

Here you can see photos after all the water exited the sink hole: