FONTANA, Calif. (KABC) — Police discovered an underground shooting range while serving a search warrant Thursday evening at the Fontana home of a known gang member, authorities said.

In a statement, the Fontana Police Department said members of its S.M.A.S.H. Gang Enforcement Unit found a manhole in the house that led to the shooting range and a hiding area.

Officers located "numerous" weapons and thousands of rounds of ammunition, including a 100-round drum for an AR-15 rifle, the news release said.

An unspecified number of suspects were arrested without incident and booked. Their names and the specific charges were not disclosed.

"Friendly message to anyone who wants to engage in illegal activity and be a member of a gang: We will never give up on keeping our community safe and free of violence," the police statement said. "We are the champions at hide-and-seek, and no manhole will help you. If you hide, we will find you. If you run, you will go to jail tired."

"We strongly recommend that you put as much effort as you did in your underground cave into becoming a productive member of society," the department added. "You will thank us later for this advice."

Story courtesy of ABC7.