LAS VEGAS (AP) — An Allegiant Airlines flight returned shortly after takeoff to McCarran International Airport in Las Vegas after a report of possible engine trouble. Allegiant spokesman Micah Lillard says flight 580 took off for Bellingham, Washington, about 9 a.m. Thursday and landed safely just than 15 minutes later, after the crew reported unusual vibrations in the left engine. Lillard says the twin-engine Boeing 757 had 129 passengers and seven crew members aboard. No injuries were reported. Lillard says passengers boarded a replacement aircraft that departed Las Vegas for Washington state just before noon.