Ten minutes into arrant mayhem in this town near the Mexican border, and the gunman, a disgruntled Iraq war veteran, has already taken out two people, one slumped in his desk, the other covered in blood on the floor.

The responding officers — eight teenage boys and girls, the youngest 14 — face tripwire, a thin cloud of poisonous gas and loud shots — BAM! BAM! — fired from behind a flimsy wall. They move quickly, pellet guns drawn and masks affixed.

The Explorers program, a coeducational affiliate of the Boy Scouts of America that began 60 years ago, is training thousands of young people in skills used to confront terrorism, illegal immigration and escalating border violence — an intense ratcheting up of one of the group’s longtime missions to prepare youths for more traditional jobs as police officers and firefighters.

Cathy Noriega, also 16, said she was attracted by the guns. The group uses compressed-air guns — known as airsoft guns, which fire tiny plastic pellets — in the training exercises, and sometimes they shoot real guns on a closed range.

“I like shooting them,” Cathy said. “I like the sound they make. It gets me excited.”

Many law enforcement officials, particularly those who work for the rapidly growing Border Patrol, part of the Homeland Security Department, have helped shape the program’s focus and see it as preparing the Explorers as potential employees. The Explorer posts are attached to various agencies, including the Federal Bureau of Investigation and local police and fire departments, that sponsor them much the way churches sponsor Boy Scout troops.

“Our end goal is to create more agents,” said April McKee, a senior Border Patrol agent and mentor at the session here.

“My uncle was a sheriff’s deputy,” said Alexandra Sanchez, 17, who joined the Explorers when she was 13. Alexandra’s police uniform was baggy on her lithe frame, her airsoft gun slung carefully to the side. She wants to be a coroner.

“I like the idea of having law enforcement work with medicine,” she said. “This is a great program for me.”

And then she was off to another bus hijacking.