ATHENS, Greece (AP) _ A powerful earthquake struck islands in western Greece on Thursday, sending panicked residents and tourists into the streets and causing some injuries and damage, officials said.

The quake, with a preliminary magnitude of 6.4, occurred at 8:15 a.m. near the Ionian Sea island of Lefkada, about 175 miles northwest of Athens, said the Athens' Geodynamic Institute. The U.S. Geological Survey put the magnitude at 6.1.

Rescue officials said the main hospital on the island treated at least 10 people for minor injuries. A fire official, Panayiotis Fourlas, said there did not appear to be widespread serious damage to buildings, but authorities had not received full reports from villages. People raced into the streets and frightened tourists tried to leave the islands.

Some roads were blocked by falling rocks and electricity was knocked out in some areas, officials said. Most Ionian islands have ferry connections to the mainland, but Lefkada is linked by a bridge.

The quake hit as residents of the Ionion islands held memorials this week for the 50-year anniversary of a series of devastating quakes that devastated the island of Cephalonia and killed 476 people.

Antonis Kalogerakis, an official at the Civil Defense Operations, said ``nothing serious'' was immediately reported.

``All's well that ends well,'' Kalogerakis said.

``It was very strong. We were all asleep in my home when it happened and some things, like the television, fell down. But the damage is small. There was some panic. It mostly scared tourists, who have not felt such intense things. We have lived through many earthquakes,'' said Ilias Georgakis, a resident of Lefkada.