BEIRUT — At least seven people died Sunday in clashes between government opponents and army troops.

The violence erupted when hundreds of Shiite youths armed with sticks and stones took to the streets, burning tires and blocking roads to protest prolonged power outages.

Army troops dispatched to quell the demonstrations opened fire into the air, and at least one person, identified as an official with the Shiite Amal movement, was killed, triggering a widespread riot of shooting and stone-throwing in which six more people died.

The riots were the latest manifestation of the tensions building as Lebanon enters its third month without a president, owing to a dispute between the pro-Western government and the Syria- and Iran-backed opposition.