Authorities warned citizens to stay out of St. Paul’s river bluff cave system after eight people were rescued Tuesday morning from a cave at Crosby Farm Regional Park.

No one was injured during the rescue about 150 feet up a steep, rocky hillside across from Watergate Marina.

“I can’t stress how dangerous this is,” said Sgt. Mike Ernster, a police spokesman. “The situation can change dramatically. … I would urge everybody to stay out of the bluff line.”

Police and fire officials said it’s unclear what the group was doing inside the cave, which also serves as a storm drainage system.

Six people between the ages of 15 and 17 were taken into police custody and will be released to their parents, Ernster said.

An 18-year-old man was expected to be booked into the county jail and faces possible gross misdemeanor trespassing charges.

Police and fire officials said an 18-year-old woman was taken to the hospital for a “situation” unrelated to Tuesday’s incident.

The group intentionally ignored rescuers who called out to them, but cooperated once they were found “huddled in a corner,” said Assistant Fire Chief Michael Gaede.

“We called out the entire time. …” he said. “They were not answering.”

According to Gaede and Ernster: Public Works employees saw the group entering the cave, and called police about 10:15 a.m.

A fire rescue crew of 20 responded to the scene and scaled the cliff side. A backup team was also on hand.

Rescuers yelled into the cave, and, hearing no response, descended 10 feet down into the cave entrance about 11 a.m.

Gaede said the air quality was good enough that rescuers did not need air supplies, but warned that carbon monoxide and low oxygen levels are lethal threats inside the caves.

The group was located 20 minutes into the search about 500 to 600 feet inside the cave system, which links to other entrances. The scene was cleared about 11:30 a.m.

Gaede said the entrance the group used had been closed off with a metal plate, and that someone had dug a new entrance around it after failing to pry it open.

Police and fire said they respond to three to six cave rescues a year.

On Nov. 18, firefighters rescued two trapped teenagers who where exploring caves on the city’s West Side.