LAS VEGAS (AP) — Federal law officers have seized more than 4,000 marijuana plants at a growing operation in Death Valley National Park thanks to a tip from hikers in the area along the California-Nevada line.

Rangers for the National Park Service and Bureau of Land Management raided the site July 3 after the hikers encountered three men installing irrigation hose near a spring in the Mojave Desert's Hanaupah Canyon.

The hikers thought the men were working on a park project but when they asked what they were doing, one told them they were growing marijuana. He reportedly said, "You won't tell the cops, will you?"

No arrests have been made.

Park Superintendent Mike Reynolds says even though California and Nevada have legalized recreational marijuana, it remains illegal at the federal level. He says grow sites decimate vegetation around springs and poison wildlife.