A teenager drowned at Rockaway Beach on Sunday night more than an hour after lifeguards cleared their chairs for the day, parks department officials said. Lifeguards and medics rushed into the water near Beach 84th Street around 7:30 p.m. after being alerted to a pair of teens in distress along the shoreline, according to authorities. The younger teen was not breathing and unconscious when medics rushed him to a hospital, where he was pronounced dead, officials said. The death was the second drowning at Rockaway Beach this year. An 18-year-old man died in the peninsula’s waters in May, before the beach opened for the season.