A strong earthquake shook southern Iceland on Thursday, injuring at least 15 people as it rocked buildings in the capital, touched off landslides and forced evacuations in outlying towns, officials and local media said.

Government officials reported that 15 to 30 people were injured, none of the seriously, when the quake hit near Selfoss, 30 miles southeast of the capital of Reykjavik. They were taken to a local health center for treatment.

The U.S. Geological Survey said the quake had a magnitude of 6.2 and hit at 3:46 p.m.

Sharp aftershocks were feared over the next few hours in the southwest of the country, and police traveled around the nearby town of Hveragerdi, 28 miles east of Reykjavik, with a bullhorn, advising residents to stay outdoors.

An Associated Press Television News cameraman in Hveragerdi reported at least two aftershocks, and said residents were beginning to pitch tents outside because they were not allowed to return home.

"It was a horrific experience. Everything inside my house is ruined," Sveinn Ingvason, a 51-year-old construction worker, told Iceland's Channel 2 from the town.

Adalheidur Gudmunsdottir, the 52-year-old director of nursing at a clinic in Selfoss, said many of her patients were frightened by the tremors.

"Some of the patients asked to moved outside," she told Channel 2. "The initial idea was to evacuate the clinic ... (but) we decided to move beds from walls and close off the elevators."

Amateur video footage aired on the national broadcaster RUV television showed rocks tumbling down the sides of jagged peaks in Vestmannaeyjum, a small archipelago off the south coast of Iceland. Residents in the capital felt buildings shake. The road between Reykjavik and Selfoss was closed by quake damage, RUV said.

Iceland, population 300,000, is a geologically unstable volcanic island in the north Atlantic.

The country's last major earthquake, in June 2000, measured 6.6. It knocked down a dozen houses but caused no serious injuries.