A fun-filled pool party turned dangerous in Mexico when organizers poured liquid nitrogen into the water, creating a poisonous fog which put one man in a coma and made eight others ill.
The thick cloud cover which spread over the pool water prevented them from breathing and caused many to pass out.
The Leon party, hosted by Jagermeister, turned serious when the four bottles of nitrogen were poured into the pool.
They only realized something was wrong when people started coughing and others fainted.
"They realized that I had fainted because they saw the tray floating alone in the pool," Jael Jimenez, a hostess at the party, said. "Otherwise, I might have drowned."
Most of those who were admitted to the hospital have been released, except for Jose Ignacio Lopez del Toro, 21, who remains in a coma.
The incident was caught on video, capturing the moment many partygoers started coughing and hacking as the gas spread. It also captured the moment they realized those in the pool were unconscious, showing some partygoers risking their own lives to jump in and save others.
One man yells "Ayudame," or "help me," in English, as he tries to pull an unconscious body from the area.
Authorities are investigating the matter and may begin pressing charges.
"We are aware of this incident in Leon, Mexico, which is currently being investigated by our headquarters in Germany," a Jagermeister spokesman said. "Fortunately, all of those who required medical attention are out of danger and recovering."