ATHENS, Greece — A strong earthquake with a preliminary magnitude of 6.5 struck southwestern Greece on Sunday, killing at least one person and injuring several others, authorities said.

The quake struck at 3:25 p.m. (8:25 a.m. EDT) near the port city of Patras, about 120 miles west of Athens in the northwestern Peloponnese, the Athens Geodynamic Institute said.

Local authorities said there were widespread reports of collapsed and severely damaged homes from the quake felt as far away as southern Italy.

One man was killed by a falling roof in the Kato Ahaia area and fire crews were trying to free a young boy and an elderly man trapped beneath rubble in region, police said.

Two families — seven people in total — who had been trapped in collapsed houses were rescued in the village of Fostaina, about 20 miles south of Patras, and in the village of Vartholomio, authorities said.

At least seven people were injured: six in the province of Ahaia and one hurt on the island of Lefkada by falling rocks at a beach, emergency officials said.

The fire service said a landslide cut off part of the Corinth to Patras highway. The power was out in parts of Patras, reports said.

Seismologists warned residents to expect aftershocks.

"There have been aftershocks and more will follow because the epicenter was close to the surface," said Gerasimos Papadopoulos, head of the Athens Geodynamic Institute's research center.

The U.S. Geological Survey said the quake had a preliminary magnitude of 6.1, while the Athens Geodynamic Institute gave a preliminary magnitude of 6.5.

Magnitudes often vary in the first hours or days after an earthquake.

Greece is one of the world's most earthquake-prone countries. In 1999, a 5.9-magnitude quake near Athens killed 143 people and left thousands homeless.