CRATER LAKE — National Park Service agents are offering a $1,000 reward for information leading to the arrest of whoever stole about 10,000 rounds of ammunition last weekend from its park ranger program.

The ammunition, which was a combination of rifle and handgun bullets, was taken from a building near park headquarters, park spokeswoman Jennifer Evans said.

The theft was discovered Monday morning when a ranger noticed a door in that building was open, and when he looked in he noticed the missing ammunition, Evans said.

That volume of ammunition was normal for the rangers, who use it for training, qualification and regular law-enforcement operations, Evans said.

The theft is considered a felony, Evans said. The Park Service's Investigative Services Branch is working the case.

The $1,000 reward is for information leading to the identification, arrest and conviction of whoever took the ammunition, the National Park Service reported.

Anyone with information can call the ISB tip line at 1-888-653-0009, text to 1-202-379-4761 or email to nps_isb@nps.gov. Tips also can be sent via Twitter to @SpecialAgentsNPS or sent to the branch's Facebook page at @InvestigativeServicesNPS. Tipsters can remain anonymous.