Russian emergency officials say a powerful earthquake has struck a Siberian region that includes Lake Baikal, but no casualties were immediately reported. The magnitude 7 quake occurred at around 10:35 a.m. on Wednesday. Its epicenter was the southern tip of Lake Baikal, west of the Siberian city of Irkutsk. The Russian television channel NTV reported that the quake caused thousands of frightened residents at apartment compounds and other buildings in Irkutsk to run onto the streets. A spokeswoman for the local branch of the Emergency Situations Ministry says the quake did not cause any casualties or major damage. Baikal is the world's largest freshwater lake by volume and a popular tourist destination.