A strong earthquake late Saturday struck a mountainous area of central Japan that hosted the 1998 winter Olympics, knocking down at least 10 homes in a ski resort town and injuring more than 20 people, officials said. According to AP, the magnitude-6.8 earthquake struck near Nagano city shortly after 10 p.m. (1300 GMT) at a depth of 10 kilometers (6 miles), the Japan Meteorological Agency said. The U.S. Geological Survey measured the quake's magnitude at 6.2. Since the quake occurred inland, there was no possibility of a tsunami. About 15 people were treated for injuries at a public hospital in the city of Omachi, three of whom were seriously injured, hospital officials told Japan's Kyodo news agency. The National Police Agency told Kyodo that at least six people were injured in Nagano city and the Hakuba ski resort. "We are trying to assess the situation as quickly as possible, and we'll do our utmost for the rescue of the injured people," Japan's top government spokesman, Yoshihide Suga, told reporters. One of the hardest-hit areas appeared to be Hakuba, a ski town west of Nagano that hosted events in the 1998 games. Ten homes collapsed there, said Shigeharu Fujimura, a Nagano prefecture disaster management official. Nine people were trapped underneath the collapsed houses, but they all were rescued, and none had life-threatening injuries, said Hakuba official Tomoyuki Shimokawa.