Six people, including a Japanese air worker, have been killed in an attack by armed men in the city of Jalalabad in Afghanistan's eastern province of Nangarhar.
"I saw there were gunmen attacking a Japanese and his security guards," a resident named Auzubillah told AFP on Wednesday, adding, "Then the gunmen left the area through a small street."
He said that he heard shooting at about 8:00 am (0330 GMT).
Photos from the scene showed a white pickup truck with a large cabin. Its side windows appeared to have been shot out.
No group has claimed responsibility for the attack. Occasional militancy continues to plague Afghanistan considering that Taliban and Daesh groups are both active there. But the Taliban were quick to deny involvement in this latest shooting.
Hours after the deadly assault, Prime Minister Shinzo Abe of Japan said he was shocked at the death of Tetsu Nakamura, to whom the Afghan people were thankful because of his contributions.
The doctor, who headed Peace Japan Medical Services, known as Peshawar Kai in Japanese, was well known in Japan for his aid work, dating back decades. He was involved in rebuilding agriculture and irrigation systems in Afghanistan.
The Peshawar Kai website states that Nakamura began aid work in Peshawar in northwest Pakistan in 1984, going on to open a clinic in a remote Nangarhar village in 1991.
The organization in 1998 established a hospital in Peshawar to serve as the group's permanent base for medical programs in Pakistan and Afghanistan.
Humanitarian groups remain on high alert in Afghanistan.
On November 24, Anil Raj, an American who worked for the UN Development Programme in Afghanistan, was killed when his vehicle was targeted in a bombing in Kabul.
In May, the Taliban targeted Counterpart International, a US-funded non-profit group working with marginalized people. Nine people were killed in the attack that was carried out in the same city.
The Taliban militants have refused to engage in any direct negotiations with the Afghan government, despite having held inconclusive talks with other parties, mainly the United States.
Peace remains fragile in Afghanistan since 2001 when US forces invaded the country to overthrow a Taliban regime that was in control at the time. Despite the announcement of plans to draw down troops on several occasions, the US is still maintaining thousands of troops on the ground in Afghanistan.