6.4 earthquake strikes Puerto Rico, island-wide blackout reported

SAN JUAN, Puerto Rico (AP) - A 6.4-magnitude earthquake has struck Puerto Rico.

It was followed three hours later by an aftershock that measured 6.0.

They are the largest in a series of quakes that have struck the U.S. territory in recent days and caused heavy damage in some areas.

The mayor of the city of Ponce said eight people were injured.

The U.S. Geological Survey said the quake hit just south of the island at a shallow depth of 10 kilometers before dawn on Tuesday.

A tsunami alert was initially issued but later canceled.

Power is down across the island, according to the power authority.