KABUL — Unknown gunmen killed six people Wednesday in the eastern Afghan city of Jalalabad, including a prominent Japanese doctor recognized by Afghanistan’s government for his service to the nation, local officials said.

Tetsu Nakamura, head of Peace Japan Medical Services, his four bodyguards and a driver were riding in the vehicle when it was attacked. Nakamura was critically wounded and later died in a hospital, while the others were killed instantly.

Nakamura, 73, was a highly respected aid worker known through eastern Afghanistan for successfully carrying out many development and agriculture projects, said Ahmad Ali Hazrat, head of the Nangahar provincial council.

“All the people in Nangahar knew him. They respected him like a local elder,” he said. “People are sad. He had served a lot.”

Japanese Prime Minister Shinzo Abe lauded the slain physician, saying he had made an “enormous contribution” to Afghanistan.

“He risked his life to make various contributions,” Abe said. “For that he was thanked by the people. I am shocked. I pray for his peace.”

The director of Peace Japan Medical Services, Mitsuji Fukumoto, told journalists that the project Nakamura was working on could not have been done by anybody but him.

“He was no ordinary doctor. He not only treated patients, he dug wells, and even drew a blueprint of waterways and drove heavy machines at the sites. He was really a rare doctor,” he said.

The gunmen fled the scene, officials said, and no group has asserted responsibility for the attack. An investigation has been launched, said Attaullah Khogyani, the Nangahar governor’s spokesman.

His death drew widespread condemnation from Afghans as well as Western diplomats.

“The Afghan government strongly condemns the heinous and cowardice attack on Afghan’s greatest friend, Dr. Nakamura who has dedicated all his life to change the lives of Afghans, working on water management, dams and improving traditional agriculture in Afghanistan,” Sediq Seddiqi, President Ashraf Ghani’s spokesman, wrote in a tweet.

The U.S. Embassy in Kabul also denounced the “unjustifiable” attack.

“Aid workers are not targets! Those responsible must be brought to justice,” the embassy said in a statement posted on Twitter.

Both Taliban and Islamic State militants are active in the eastern province of Nangahar. The Afghan government said it defeated the Islamic State there two weeks ago after hundreds of the terrorist group’s fighters surrendered. The Taliban still controls large areas, however.

The incident happened a week after a grenade attack on a U.N.-marked vehicle in Kabul. One employee of the organization was killed and two other U.N. employees were among five people wounded in that attack.

There was an outpouring of support for Nakamura on social media in Japan, where he was a well-known and respected figure. In 2003, he won the Philippines’ Ramon Magsaysay Award, sometimes known as Asia’s Nobel Peace Prize. The citation recognized “his passionate commitment to ease the pain of war, disease, and calamity among refugees and the mountain poor of the Afghanistan-Pakistan borderlands.”

Nakamura first came to Afghanistan to climb its mountains and then in 1984 volunteered at a hospital in Peshawar in Pakistan near the border, where he headed the leprosy unit. He later organized health centers as Afghan refugees flooded into Pakistan during the Soviet occupation.

Afterward, in the 1990s, he founded and ran health clinics in remote parts of Nangahar province. More recently, his focus shifted to building water systems to combat widespread drought.

“We choose not to go to places where everyone is willing to go, but rather to places where help is desperately needed and no one else is willing to go,” reads a quote from Nakamura on his organization’s website.

Denyer reported from Tokyo. Paul Schemm in Dubai contributed to this report.