Authorities are still investigating a shooting that left three people dead in Spotsylvania County.Preview: A Frontier Airlines flight has been cleared after it was forced to sit on the runway at Dulles International Airport for several hours. Flight 4708 from Atlanta landed at Dulles around 2:30 yesterday afternoon. The flight crew reported a beeping noise coming from the cargo area, which led authorities to remove passengers and complete a precautionary search of the aircraft. Nothing was found and passengers were then allowed to collect their baggage at the main terminal.