Brazilian authorities said Sunday one firefighter had died in a cave, as first responders raced to rescue eight others still trapped underground after the cave roof collapsed while they were training inside.
The accident occurred as a group of 26 firefighters were on a training exercise in a cave near the city of Altinopolis, the Sao Paulo fire department said on Twitter.
"The roof of the cave collapsed," trapping part of the group, it said.
The department tweeted Sunday afternoon that "eight people are missing, one dead," without disclosing the victim's identity.
Local press reported the victim was a woman.
A previous report said 15 firefighters were still buried, and that three of the victims who were rescued suffered fractures and hypothermia.
Five people in total were taken to a local hospital and discharged, according to the mayor's office.
Police and emergency health teams have joined firefighters in a desperate effort to free those still trapped, but the work has been hampered by heavy rains.
Access to the remote site is difficult, and threats of new collapses have complicated the rescue.
Sao Paulo Governor Joao Doria said on Twitter he would provide "all the support and resources necessary for the rescue of the victims."
Speaking to GloboNews, Cristina Trifoni, mother of one of the instructors participating in the training, explained that the group had planned to spend the night inside the cave.
"What happened is that the entrance to the place they were in collapsed. I'm desperate," she said next to relatives of other firefighters who anxiously awaited word on the rescue effort.
Altinopolis is known for its caves, a major regional tourist attraction.
