Gunfire erupted as throngs were celebrating a mild St. Patrick’s Day along a popular downtown canal in Indianapolis and at least five teenagers were wounded by shots, two critically, police said. The shots rang out Saturday night near the Downtown Canal on the west side of this Midwest city shortly after 10 p.m., police spokeswoman Linda Jackson said in a statement. The canal with its pedestrian pathway and restaurants dotting the area is a popular gathering place and had been thronged during the weekend, reports said. Police said patrolling officers were already downtown and had gone to check on a report of young people fighting when they suddenly heard gunfire nearby, according to the statement.