Lockheed’s memorial for contractors. (Lockheed Martin)

Teofilo Evans and Sidney Hanspard, both Air Force veterans turned Lockheed Martin contractors, were in the break room at an Afghanistan base in April last year when disaster struck.

They, along with David Nicholson, another Lockheed contractor, heard a rocket nearing and made a run for the bomb shelter. The three, who were on the battlefield to help soldiers use Lockheed’s blimp-like surveillance system, made it outside, but Evans, 47, and Hanspard, 53, were killed. Nicholson lost his legs.

The two deaths marked the most recent casualties overseas for Lockheed, which has lost three other employees in Afghanistan and Saudi Arabia.

Last week, the company unveiled a memorial at its Bethesda headquarters to honor employees who have died in the line of work. Contractors and industry observers alike say the public has been slow to recognize the toll the wars in Iraq and Afghanistan have taken not only on soldiers but on their employees, who often work alongside troops.

Robert J. Stevens, Lockheed’s chief executive and chairman, said the company decided to erect the memorial, a large granite wall with a pillar for each of the employees lost, after an employee suggested it last year.

“I don’t believe there’s a great deal of public awareness,” he said in an interview after the ceremony. “We don’t broadcast the heroic actions of these people, [but] they ought to be properly remembered.”

Lockheed’s employees are among thousands who have died overseas since late 2001.

Contractor fatalities in Iraq and Afghanistan have numbered 2,694 from 2001 through the first quarter of 2012, according to research compiled by Steven L. Schooner, who co-directs the George Washington University Law School’s government procurement law program, and his former research assistant Collin D. Swan. That number represents about 30 percent of the total U.S. fatalities.

New York-based L-3 Communications has seen the highest number of casualties at 374, according to Schooner. A company spokeswoman noted that the majority of the units that have lost the most employees have become part of Engility, a services business spun off from L-3 earlier this year.

In a statement, L-3 said it mourns the loss of its employees, who “came forward to make a significant contribution while displaying courage and selfless service.”

Increasingly, contractor employees have comprised a larger percentage of those killed. In Afghanistan, for instance, fewer than 10 percent of those killed before 2005 were contractor employees. In 2011, contractor employees made up almost half of the fatalities, Schooner’s research shows.

Still, the deaths can create a difficult situation for companies, said Doug Brooks, president and founder of the International Stability Operations Association.

“It’s not the sort of business press release you’d put out,” he said. “There’s also the perception they don’t want to be seen using it for business development purposes.”

Stevens said Lockheed sought to create a meaningful day and memorial for the families of those lost. All of the employees honored had family members in the audience last week.

Tammy Evans, Teofilo Evans’s widow, traveled from Texas with their young children, arriving early to see Washington for the first time.

“He lived to do what he wanted to do,” she said of her husband, a military veteran who had planned to be a stay-at-home dad before joining Lockheed Martin. “His skills were needed.”