He covered the Ebola epidemic in West Africa. He was there to watch the Sundarbans of India swallowed up by climate change. In South Sudan, he bore witness to a food crisis, the fallout from a devastating civil war.

In the aftermath of his death Sunday from a grenade attack while covering a story in Afghanistan, David Gilkey was remembered by NPR's top news executive as a globe-trotting photojournalist with such a willingness to travel that he was a foreign bureau unto himself.

"He was this mobile bureau who could go wherever he was needed — and did," said Mike Oreskes, NPR's senior vice president of news. "It was because he could handle all of these difficult circumstances with good judgement and common sense and a real touch of humanity. He was very important as an individual journalist, and he was very important as a representative of our core mission."

Gilkey's sensitivity was touted by his colleagues in the hours after his death alongside Zabihullah Tamanna, NPR's Afghan translator. His friends remembered his most empathetic photos — an image of a little girl in Afghanistan at snacktime, a dignified portrait of an army vet with his wife, a little boy in West Africa lying on the ground, wracked by Ebola.

"If you go back through his work, from Afghanistan and Iraq, West Africa during Ebola, the Haitian earthquake, there's just a humanness in what he captures," Oreskes said. "Whether it's the soldiers or the civilians or the earthquake victims or the incredible story of the young boy dying of Ebola...this guy just had an eye and a heart for humanity. And I think that's why he kept going back."

Foreign news has become increasingly central to NPR's mission around the world as diminishing financial prospects have forced many U.S. news organizations to decrease their commitment to international coverage. In 2014, NPR announced its 17th international bureau, based in Seoul, South Korea. In many ways, Gilkey was the radio network's 18th bureau, Oreskes said.

Gilkey's last assignment in Afghanistan, undertaken with three colleagues from NPR, was to offer an in-depth report on the state of the war now that it had largely been turned over to the Afghani people, Oreskes said. The two remaining NPR journalists in the country are OK, and NPR is hoping to make Gilkey's reporting available as soon as possible.

"Some of his work may have been lost in the attack," Oreskes said. "We don't know yet. We know that in the last couple of days, he called in and was very excited about the material he was gathering."

Gilkey and Tamanna were the first journalists in NPR's 46-year history to die on assignment. The radio network is planning to review the reporting trip, as is routine with international assignments, but Oreskes doesn't expect the analysis to reveal any faults in the planning process. Instead, he said, the trip was further evidence of NPR's emphasis on international coverage, which sometimes comes at a high cost.

"These journalists were deeply committed to the work they were doing," Oreskes said. "They understood that it was dangerous. But they believed, in a very profound way, that this was an important story to tell."