SAN'A, Yemen—Witnesses to the fatal shootings last month of two Yemenis by American government officials said they saw a Western-looking man pull a gun from his belt and shoot both Yemenis dead during what appeared to be a kidnapping attempt at a barber shop.

The firsthand accounts bear similarities but also what appear to be slight differences with an incident the U.S. State Department revealed Saturday in which it said two U.S. embassy officers killed a pair of armed men who were attempting to kidnap them last month. The...