The head of a Japanese aid agency and five other people have been killed in an ambush in eastern Afghanistan

Among the victims was Tetsu Nakamura, 73, the respected physician and head of Peace Japan Medical Services, who had recently been granted honorary Afghan citizenship for his decades of humanitarian work in the country.

“I am shocked that he had to die in this way,” Japan’s prime minister, Shinzo Abe, told a news conference in Tokyo after news of Nakamura’s death alongside five Afghan colleagues was disclosed. “He risked his life in a dangerous environment to do various work, and the people of Afghanistan were very grateful to him.”

Hundreds of Afghans posted photographs of Nakamura on their social media pages, condemning the killing and underscoring the esteem in which he was held.

The gunmen fled the scene and police have launched a search operation to arrest them, Sohrab Qaderi, a member of the governing council in the province of Nangarhar, told Reuters, adding that he believed Nakamura had been targeted for his work.

“Dr Nakamura has been doing great work in the reconstruction of Afghanistan, especially in irrigation and agriculture,” he said.

Among those killed in the attack on Wednesday were the doctor’s bodyguards, a driver and a passenger, a hospital spokesman said.

According to reports, Nakamura and team members were traveling to the provincial capital, Jalalabad, at about 8am. The Taliban denied responsibility for the attack.

Nakamura, who was seriously wounded in the chest, died shortly after, while being airlifted to the Bagram airfield hospital in the capital, Kabul, said Gulzada Sanger, the hospital spokesman.

Nakamura had headed Peace Medical Services, a Japanese charity based in Nangarhar, since 2008. He came to Afghanistan after a Japanese colleague, Kazuya Ito, was abducted and killed.

In April, the Afghan president, Ashraf Ghani, granted Nakamura honorary citizenship of Afghanistan.

Nakamura had worked in the region since 1984, initially providing aid in Peshawar, in north-west Pakistan, before opening a clinic in Afghanistan in 1991.

No one immediately claimed responsibility for the attack, the second in as many weeks targeting aid workers in Afghanistan.

In late November, an American working for the UN mission in Afghanistan was killed and five Afghans, including two staff members of the mission, were wounded when a grenade hit a UN vehicle in Kabul.

On Monday, a gunman opened fire on a vehicle in Kabul, killing two intelligence officials and wounding three others. No one claimed responsibility for that attack, but both the Taliban and the Islamic State affiliate have been behind such attacks.