SAN JUAN, Puerto Rico — Three people have been killed and three others injured during a shooting at a gas station in Puerto Rico.

Police say several men opened fire on the group early Saturday in the eastern town of Las Piedras. It is unclear what prompted the shooting.

The U.S. territory had already seen five similar shootings reported this year in which at least three people died.

Police have said most of the fatal shootings are related to drug trafficking. The island of 3.7 million people reported a record 1,117 killings in 2011.