A group of college students trapped for hours by rising water in a Kentucky cave waded through neck-deep water to get out, authorities said Thursday.

The 19 people trapped included two police officers who tried to reach them, Hart County Emergency Management Director Kerry McDaniel said. The students from Clemson University in South Carolina were exploring the cave when torrential rains hit the region, he said.

The students went into Hidden River Cave about 10 a.m. CDT Thursday and emerged about 4:30 p.m., McDaniel said. They walked out on their own and were checked for hypothermia but declined further medical attention, he said.

"When they came out of the cave, they were neck-deep in water," he said.

The students had planned a five-hour trip exploring the cave but got trapped by rising water from heavy rains that started after they entered the cave, McDaniel said.

Four other people were able to escape earlier, Horse Cave Fire Chief Donnie Parker said. He didn't have details about how they got out.

The only light the trapped people had was from headlamps they wore, McDaniel said.

Authorities had no communication with the people inside the cave.

More than 150 rescue workers had rushed to the scene to begin rescue operations.