Two gunmen on a motorbike on Tuesday shot dead a Russian military advisor and wounded another as they left a hotel in the Yemeni capital, a security official said.
The gunmen fled after opening fire on the experts, who worked as advisors to the Yemeni army, the official said.
The Russians were gunned down as they walked out of a hotel in Baynouna street in southern Sanaa. Security forces immediately cordoned off the scene of the attack.
Witnesses said that the two were felled by shots to their chests.
The two men were dressed in civilian clothes, hotel manager Mohammed al-Shami said, adding that they were waiting for two other Russian colleagues to come out to share a taxi.
The four advisors have been staying at the hotel for some four months, he said.
"We heard the shooting. When we rushed out, we found the two in a pool of blood," Shami said.
Two vehicles from the nearby presidential palace arrived around 10 minutes after the attack and took away the casualties and the two other advisors.
Many Russian experts are believed to serve as advisors to the Yemeni army, which uses mainly Russian weapons.
Hit-and-run assassinations are frequent in Yemen and are mostly blamed on Al-Qaeda militants, or stem from tribal and political conflicts.
Last week, a Yemeni MP representing the Zaidi Shiite rebels was shot dead in a similar attack.
Abdel Karim Jadban died after two gunmen riding a motorbike shot him as he walked out of a Sanaa mosque.