Sanaa: A Lebanese Red Cross employee was gunned down in his car in war-torn Yemen's southern city of Taez on Saturday, the ICRC announced.
"I'm shocked, outraged and profoundly saddened by the killing of my colleague and friend Hanna Lahoud," tweeted Robert Mardini, Middle East director for the International Committee of the Red Cross.
"We @ICRC condemn this senseless act in the strongest possible terms," he wrote. "My thoughts go out to Hanna's wife and family in #Lebanon."
The ICRC said Lahoud, who was charge of prisoners' affairs in Yemen, was on his way to visit a prison when his car came under attack by unknown gunmen.
He died in hospital of his wounds, while colleagues in the same car were unharmed, it said in a statement.
The aid worker was killed by multiple gunshots to the heart, according to a hospital source who spoke on condition of anonymity.
The back window of the car was completely shattered in the attack in the Zabab district of Taez, said an AFP photographer at the scene.
Most of Taez is controlled by forces loyal to President Abedrabbo Mansour Hadi, while Houthi rebels hold many parts of the surrounding area.
A colleague of Lahoud's mourned his death on Twitter:
"He saved hundreds of lives as a volunteer for the Lebanese Red Cross. He made silly jokes. He had a wonderful voice... He also beat cancer 2 years ago. Today an idiot took his life," tweeted ICRC regional spokeswoman Marie Claire Feghali.
The United Nations says the conflict in Yemen has triggered the world's worst humanitarian crisis, with over 22 million people dependent on aid and 8.4 million on the verge of famine.