A Japanese doctor who devoted his career to improving the lives of Afghans has died, after being injured in an attack in eastern Afghanistan. Officials say gunmen shot Tetsu Nakamura, 73, while he was travelling in a car to monitor a project. Five other Afghans were also killed in the attack, which happened in the city of Jalalabad. Dr Nakamura headed a Japanese charity focused on improving irrigation in the country. In October this year, he was awarded honorary citizenship from the Afghan government for his humanitarian work. No-one has yet claimed responsibility for the attack and the reason behind the attack remains unclear. The US Embassy in Kabul has condemned the attack, saying "aid workers are not targets". Attacks of this kind are fairly common in Afghanistan. Last week, an US national working for the UN in Afghanistan was killed in a blast targeting the UN vehicle. Research by the BBC found that an average of 74 men, women and children were killed every day in Afghanistan in the month of August alone. How did the attack unfold? Dr Nakamura was travelling in a vehicle in Jalalabad city in the eastern province of Nangarhar on Wednesday morning when he came under attack. He was shot on the right side of his chest and was in the process of being transferred to a hospital near the capital Kabul when he died at Jalalabad airport, officials told AFP news agency. His three security guards, a driver and a colleague of his were also killed, said Attuallah Khogyani, a spokesman for Nangarhar's governor. Photos from the scene showed a white pickup truck with at least three bullet holes in its windscreen. Bullet holes are seen in the window of the vehicle He was attacked while inside this white pickup truck on Wednesday Sohrab Qaderi, a member of the provincial council in Nangarhar told Reuters that the gunmen fled the scene. Who is Tetsu Nakamura? Dr Nakamura was born in the Japanese city of Fukuoka in 1946. He went on to become a doctor in Japan but eventually moved to Pakistan in 1984 to treat patients with leprosy. Two years later, he headed to Afghanistan, where he would go on to open his very first clinic in a remote village in Nangarhar and establish his NGO, the Peace Japan Medical Services (PMS). At its peak, PMS operated 10 clinics providing help for leprosy patients and refugees amongst others. Dr Nakamura had also heavily been involved in the construction of wells and irrigation in villages where many suffered from cholera and other diseases because of a lack of clean water. In 2003, he won the Ramon Magsaysay Awards, widely regarded as the Asian equivalent of the Nobel Prize. Dr Nakamura has been recognised for his work In 2014, Dr Nakamura told news outlet the Japan Times that he took a different route to work each day to ensure his safety. However, he also added that the best precaution he could take was to "befriend everyone". "I've tried to make no enemies. . . . The best way is to befriend everyone, even if that makes people think I lack principles. Because the people are the only thing I can depend on there," he had said. "And that's surprisingly more effective than carrying a gun." What has been said about him? Many in Afghanistan are now paying tribute to Dr Nakamura. The Ambassador of the Netherlands Embassy in Kabul Ernst Noorman called the killing "senseless", saying Dr Nakamura had dedicated his life to the "peace and development of Afghanistan". Sediq Sediqqi, a spokesman for Afghan president Ashraf Ghani echoed the sentiment on Twitter. "[He] dedicated all his life to change the lives of Afghans." "He came all the way from his homeland Japan to Afghanistan. He provided drinking and irrigation water to [the] poor," said one commenter on Twitter. "Today Afghanistan lost a true hero and a public servant," another said. "He devoted his life to the medical treatment of vulnerable people in Afghanistan."