BEIJING (Reuters) -A China Eastern Airlines Boeing 737-800 with 132 people on board crashed in mountains in southern China on a domestic flight on Monday after a sudden descent from cruising altitude. Media said there were no signs of survivors. The airline said it deeply mourned the passengers and crew, without specifying how many people had been killed. Chinese media showed brief highway video footage from a vehicle’s dashcam apparently showing a jet diving to the ground behind trees at an angle of about 35 degrees off vertical. Reuters could not immediately verify the footage. The plane was…