Unidentified gunmen shot dead a female employee of the UN refugee agency (UNHCR) in Somalia's capital Mogadishu on Monday, another person also died in the attack, a UN statement said.
"It is with great sadness that UNHCR has learned of the killing of one of our colleagues, Amina Noor Mohamed, this afternoon in Mogadishu, Somalia," the UNHCR statement said.
Mohamed was killed by "unknown gunmen while travelling in a private vehicle driven by a staff member from a UNHCR partner organization who also lost his life in the attack."
No group claimed responsibility for the attack, however, aid workers including UN staffers have previously been targeted by Al Qaeda affiliated Al Shabab militants.
Mohamed, worked in Mogadishu since 2011, and left behind two young children, aged two and three months, UNHCR said.
UNHCR chief Antonio Guterres said the attack "serves as another stark reminder of the dangers many humanitarian workers face in their daily work." Guterres added that UNHCR staff would observe a moment of silence for Mohammed at the agency's headquarters in Geneva on Tuesday.
In April, four employees of the UN's children's agency (UNICEF) were killed when Al Shabab militants set off a huge bomb that ripped through a staff bus in the northeastern town of Garowe.
The insurgency says the UN is a "colonisation force in Somalia."