Three teens die of carbon monoxide in Minnesota cave
(CNN) -- Three teenagers died Tuesday after being overcome by carbon monoxide fumes when they were exploring a cave on the bluffs of the Mississippi River in St. Paul, Minnesota, police said.
Officer Paul Schnell, spokesman for the St. Paul Police, told CNN in a phone interview that a group of five high school students -- four boys and a girl -- entered one of the many caves along the banks of the river.
One boy who noticed he was becoming lightheaded inside the cave managed to get out and get help. A rescue team from the St. Paul Fire Department went into the cave with special breathing equipment and managed to revive another boy.
"He's now in a hyperbaric chamber in a local hospital," Schnell said.
The three other teenagers were already dead, he said.
Schnell said fire department officials reported that the carbon monoxide levels inside the cave were extremely high, and the air contained only 15 percent oxygen.
"There was no way of getting fresh air," said St. Paul Fire Marshal Steve Zaccard. "The cave had been sealed by the city, but they dug it out."
City workers have tried to seal most of the entrances to the cave complex, according to rescue officials.
Zaccard said the high carbon monoxide levels were likely the result of someone starting a fire in the cave in recent weeks, since there was no evidence of smoldering ashes. With little circulation of fresh air, the deadly fumes remained.
In 1992, two girls were killed by carbon monoxide poisoning in a cave nearby.
"One of the most sad things about today's incident is that not 50 yards from the cave they were in there was a warning sign put up by the parents of the two dead girls" from the 1992 incident, Schnell said.