KABUL, Afghanistan (CNN) -- Motorbike gunmen killed a foreign aid worker in Kabul Monday, the Afghan Interior Ministry has said.
Aid worker Gayle Williams was one of 23 expatriates who worked for SERVE Afghanistan.
In a separate incident, two German soldiers and five Afghan children were killed when a suicide bomber struck an Afghan-German military convoy in northern Afghanistan, the provincial governor in Kunduz said.
Gayle Williams, 34, had dual British and South African nationality and worked for SERVE Afghanistan (Serving Emergency Relief and Vocational Enterprise), an inter-denominational Christian charity that helps the disabled, the organization's chairman said in a statement.
Williams was shot in the western part of the city, Interior Ministry spokesman Zemarai Bashary said, while walking to work. She died shortly after the attack, SERVE Afghanistan chairman Mike Lyth said.
"She was a person who always loved the Afghans and was dedicated to serving those who are disabled," Lyth said. "Needless to say, we are all in shock." Williams was one of 23 expatriates who worked for SERVE Afghanistan, which also employs 450 Afghans in the country.
A statement on SERVE Afghanistan's Web site -- attributed only to "C and E" -- described Williams as "one of the inspiring people of the world who truly put others before herself."
"She was killed violently while caring for the most forgotten people in the world; the poor and the disabled," the statement said. "She herself would not regret taking the risk of working in Afghanistan. She was where she wanted to be -- holding out a helping hand to those in need."
United Nations Secretary-General Ban Ki-moon condemned her killing as well as the recent killings of two U.N. aid workers in Somalia.
"The secretary-general deplores these acts of deliberate violence against those who are making every effort to alleviate the dire suffering of Somali and Afghan citizens," Ban's spokeswoman Michele Montas said at Monday's daily briefing in New York.
The Taliban claimed responsibility for the death, saying on its Web site that it killed the "foreign woman" for preaching Christianity in the country and adding that it had been following the woman for some time.
In August, aid groups in Afghanistan said in a report that attacks on aid workers have forced them to scale back relief work.
The bomber who attacked the Afghan-German convoy was riding a bike when he detonated his explosives as the vehicles traveled outside the northern Afghan city of Kunduz, Gov. Mohammed Omar said.
Two German soldiers and two Afghan civilians were wounded, according to Omar. The Taliban claimed responsibility for the attack in an Internet posting, claiming to have killed 12 German soldiers.
The Afghan and German forces went to Chahar Dara district to investigate enemy activity in the region when they were attacked, Omar said.
NATO's International Security Assistance Forces confirmed that a suicide attack in Kunduz province killed two of its soldiers and five local children, but did not reveal the ISAF soldiers' nationalities, as part of its standing policy.
ISAF spokesman Brig. Gen. Richard Blanchette said: "Acts such as this, which offer nothing but violence and death, will not deter us in our commitment to create a better Afghanistan."
NATO said one ISAF soldier and a civilian were also wounded in the attack.
The German Defense Ministry in Berlin confirmed a bomb attack near a base that houses a German provincial reconstruction team in the town of Kunduz, a ministry spokesman said. It had no information on casualties.
Germany has committed 3,200 troops to support NATO's mission in Afghanistan. The latest deaths bring to 25 the number of German soldiers who have died in the Afghan war since 2002.
Journalist Farhad Peikar and CNN's Frederick Pleitgen in Berlin contributed to this report.