The quake, with a preliminary magnitude of 6.8, struck at 2:20 p.m. (7:20 a.m. EST) and was centered near the Congo-Tanzania border, about 600 miles southwest of the Kenyan capital, the U.S. Geological Survey said.
The USGS said the quake was located about six miles below the surface, and shook the ground in at least three Kenyan towns, including Nairobi. It also was felt in the Kenyan coastal city of Mombasa.
"We felt the tremor in our offices. People fled their buildings to save their lives, but so far we have no reports of casualties," said Elmon Mahawa, the regional commissioner for Kigoma, a Tanzanian town on the shores of Lake Tanganyika.
In Bujumbura, the capital of the central African nation of Burundi, an Associated Press reporter felt the three-story building sway in two waves of the quake.
The region is located along the Great Rift Valley, which runs for 3,000 miles between Syria and Mozambique and passes through the Dead Sea, below Jerusalem's eastern hills.