Strange sound from sky near internation airportFour of us just returning from vacation to Newark International airport. Took bus to long term parking lot G (now lot P) to get our car. Had trouble locating car due to writing down incorrect row. Wife and friend went one direction and my son (16 years old) and myself went another direction to locate car. While my son and myself were walking around in the parking lot we heard this very loud sound similiar to a jet engine which came from 5 or 6 different directions at one time in about a 4 second time frame. The two of us automatically looked into the overcast sky thinking it was some type of jet since they were landing right over our heads. After thinking of what we just heard it was imposible for this to be a jet since the sound was coming in from many different directions to the point where we were standing in this very large parking lot in a very short time. We had looked into the sky but I noticed nothing as my son said he noticed a rectangle object that was gray in color which vanished as fast as the sound we both just heard. Not sure what this was but it has to be the strangest thing I every experienced in my life (48 years old). Not that my son and I didn't believe in UFO's now that I heard this and my son did see something in the sky we have had our own experience which if it wasn't for both of use being together when this happened I don't know if I would beleive it myself.