The strongest earthquake to hit California in 20 years caused minor injuries and damage in a town near the quake's epicenter. The quake struck Thursday morning in the x Desert, about 240 kilometers northeast of Los Angeles. Scientists say it measured 6.4 in magnitude. The United States Geological Survey defines magnitude as a number that represents the relative size of a quake. An area near the small town of x was most affected by the quake. But it was felt by people in areas as far away as Los Angeles, and Las Vegas in the neighboring state of Nevada. Officials said more than 80 aftershocks shook the town and nearby areas by Friday. One of them had a magnitude of 4.5. These aftershocks were expected to continue. The Fire Chief in California's x County, x, told reporters only a few minor injuries were reported. He said the injuries came from broken glass and objects falling inside local businesses. x added that some hospital patients were moved from the town's main hospital because it received damage. Two houses caught fire from broken gas lines. Some power lines went down, leaving thousands of people without electricity. The quake was blamed for some small grassfires and damage to roads. California Governor x declared a state of emergency for x County, meaning the area can receive state aid and recovery assistance. x is a restaurant worker in x. She told the Associated Press: The earthquake almost gave me a heart attack. She described a rolling feeling inside the building. And all of a sudden, everything started falling off the shelf, she said. Video images of one business show the floor filled with broken bottles, boxes and food products that fell from shelves. x is with the California Institute of Technology. She said the earthquake was the strongest to hit California since a 7.1 quake struck the area on October 16th, 1999. This has been an extremely quiet abnormal time, x said. This type of earthquake is much more normal. The long-term average is probablyonce every five or ten years somewhere in southern California.