Smoke rose from Beirut’s southern suburbs Saturday morning and the streets were empty after the area was pummeled overnight by heavy Israeli airstrikes. Attacks on Hezbollah targets by fighter jets Friday continued into the early hours Saturday after the army said it told residents to evacuate three buildings it was targeting. Hours before the strikes, Prime Minister Benjamin Netanyahu addressed the United Nations, vowing that Israel’s campaign against Hezbollah would continue — further dimming hopes for an internationally backed cease-fire. Netanyahu abruptly cut his United States visit short and returned to Israel.