Complex sentence: Meegar's angst then apparently causes the elevator to fall to the underground parking lot levels, killing all but Meegar, who walks away unhurt but startled as all the car alarms go off around him.
Split into simpler sentences: Meegar's angst then apparently causes the elevator to fall to the underground parking lot levels, killing all but Meegar. He is able to walk away unharmed, but is then startled as all the car alarms go off around him.