Just before 3 p.m. Saturday, a white Chevy Blazer pulled up to the arrival curb outside Terminal A at Mineta San Jose International Airport. Two men dressed in black parked the SUV, switched on its hazard lights and approached the information desk to inquire about American Airlines Flight 1205 from Dallas. Both carried assault rifles strapped across their chests, with handguns in their holsters.

A volunteer at the desk politely told them the plane was due at 3:02 p.m. And another volunteer asked one of the armed men, “Are you one of the people who ride on the plane” looking for terrorists? “No,” he replied.

Then the pair casually waited near the escalator that ferries travelers to the luggage carousels.

“I wondered if they were going to shoot somebody coming off the plane,” one volunteer said. She resolved to dive under her desk if that happened.

Still, she was worried. “I didn’t know if this was proper, if people are allowed to walk into an airport with assault rifles and just stand there.”

It appears that airport travelers that day either figured the pair’s mission was benign, or perhaps thought they were part of a ninja movie. San Jose police said they received no calls inquiring about the men with rifles.

Simply leaving a bag unattended for a few minutes can cause airport security guards to panic. But apparently it isn’t illegal to carry weapons into the nonsecure areas of Mineta San Jose Airport — or most other U.S. airports.

The two volunteers — who asked not to be named because airport officials did not give them permission to speak publicly — said they were unsure what to do.

After 15 years of assisting in the terminal, they said, they know what to do when someone loses an ATM card (call 911), when passengers’ rides don’t show up (lend them a cell phone) and when handed prohibited carry-on items (mail the items to the passengers’ homes). But they had received no training on how to handle heavily armed visitors.

A parking control officer at the airport asked his supervisor what he should do.

The response, according to one of the volunteers: “Next time that happens, have one of them sit in the car while the other one comes in.” The airport prohibits unattended cars at the curb, especially under the current orange alert level.

Soon, the armed pair greeted another man wearing a baseball cap after he descended the escalator. Together they picked up about a half-dozen pieces of luggage, loaded them into the white SUV and drove off.

It turns out the men with the assault rifles were from Lawrence Livermore National Laboratory and were meeting another security staffer returning from assignment, lab spokesman Don Johnston said.

San Jose police and airport officials, who were unaware of the armed greeting until questioned by the Mercury News on Sunday, said protocol is for a law enforcement agency to give notice when sending armed personnel into another agency’s jurisdiction, according to police Lt. Mike Sullivan.

An airport videotape showed the men in the baggage area for seven or eight minutes, airport spokesman David Vossbrink said.

Johnston said that it isn’t unusual, especially on weekends, for Lawrence security guards to meet personnel at airports. And yes, he said, the security staff members dress in what police call “battle dress uniforms”: dark clothing with logos that are difficult to see.

In a flurry of phone calls Sunday afternoon, San Jose police and the U.S. Department of Energy worked out a clear notification protocol, Sullivan said.

That left one of the volunteers relieved, yet incredulous.

“I couldn’t believe,” she said, “that man was so valuable it took two men with assault rifles to escort him to Livermore.”

Contact Sharon Noguchi at 408-271-3775.