A tour guide has been cited for leading a group into a prohibited area at Halemaumau Crater, an area closed to the public since 2008.

At about 12:30 a.m. Monday, park rangers caught the tour guide and 13 clients entering the area. Rangers issued citations to the guide and clients for violating the terms of the closure before escorting them out of the park, according to Hawaii Volcanoes National Park officials.

The tour guide, 44, who is employed with a France-based tour company called Adventure et Volcans, also was cited for operating a non-permitted business in the park and creating a hazardous condition, officials said. He faces a maximum fine of $5,000 and six months in jail for the violations. His name was not released.

Each client faces a $130 fine for violating the terms of the closure.

Hawaii Volcanoes National Park spokeswoman Jessica Ferracane said, “They’re really putting themselves in hazardous situations.”

“There’s a lot of explosions that have been happening at the summit,” she said.

Last year, spattering destroyed U.S. Geological Survey scientific equipment and instruments. Halemaumau Crater and parts of the rim trails has been closed to the public since the 2008 summit eruption because of hazardous volcanic conditions that include collapses of crater walls.

Since July 2016, park rangers have issued 35 citations to individuals entering closed areas at Halemaumau.

At closed areas of Kamokuna, where a high volume of lava is flowing into the ocean, nearly 100 citations were issued in the same time period, park officials said.