Unknown gunmen killed a German embassy guard Sunday in an attack on a diplomatic vehicle in the Yemeni capital, a security official said.
The two gunmen tried to kidnap the German citizen as he left a supermarket in Sanaa, killing him when he resisted before fleeing in a car, the official added.
In a separate incident, armed tribesmen abducted a UNICEF employee in a northwestern suburb of Sanaa, other security officials said.
They said the employee for the UN agency, a Sierra Leone national, was in his car with a Yemeni driver when they came under attack.
Armed assailants pushed the driver out of the vehicle and sped away in the car with the UNICEF employee on board, the officials added.
All officials spoke on condition of anonymity because they were not authorized to brief reporters.
Abductions are frequent in Yemen, an impoverished nation where armed tribesmen and al-Qaeda-linked militants take hostages in an effort to swap them for prisoners or cash.
Yemen is engaged in a rocky political transition since longtime autocrat Ali Abdullah Saleh stepped-down in 2012 following mass popular protests.
The country's political turmoil has caused a security vacuum, which al-Qaeda has used to seize large swaths of territory across the restive south.