LOS ANGELES — A strong earthquake that shook southern California left two people dead, injured more than 100 others, and damaged more than 650 buildings - all in about 10 seconds.The quake early Friday knocked homes off their foundations, toppled chimneys, shattered windows, triggered rock slides on mountain roads, swayed high rises, knocked out electricity, and served as a rude wake-up call to thousands. The Caltech Seismology Laboratory in Pasadena said the quake measured 6.0 on the Richter scale and was centered 8 miles north of Sierra Madre, a foothill community in the San Gabriel Mountains 15 miles northeast of Los Angeles. The quake's epicenter was 7 miles below ground. The cities of Monrovia, Pasadena, Sierra Madre, and Arcadia were hardest hit, with damage expected to climb in the multimillions of dollars. A preliminary damage estimate for Pasadena alone pegged losses at a minimum of $10 million but could climb to $40 million or more.