One light being chased by three helicopters.

One light, not super bright though, being chased by three helicopters.  
At first I heard what sounded like an army tank going down the street and I ran outside to see three helicopters flying almost directly over my house and they were very low.  
You could see the flashing lights on the helicopters, and I could see in front of them a smaller light, that was not flashing at all and they were following it.  
Just as quickly they went over the trees across the street and I could not see them anymore.  
You could hear the helicopters for about 30 seconds or so then the sound was gone.  
It's night here so I could not see any markings at all on the helicopters.