Possible Gunshots Near Cortelyou & E 17th Street

A neighbor who lives on Cortelyou near E 17th Street wrote us about recurring incidents near his home that he and his neighbors believe to be someone firing a gun. He says:

On Saturday July 6, my wife and I, as well a number of people from my building, heard seven gunshots in quick succession in the middle of the night.
We called the police and they came and scoured the area for shell casings. They found nothing, and there were no reports of anyone or anything being shot. The general consensus is that someone was shooting in the air, perhaps on a roof somewhere.
Monday night there was one lone shot late in the evening, followed by two more shots at around 4am. This time I didn’t call the police since I was exhausted and fell asleep shortly after each shot. It seems like someone has a gun in the area and spends his nights using it.
While Monday there was a thunderstorm, the sounds I heard were distinctly gunshots. Several neighbors heard them as well.

The 70th Precinct has confirmed that no shells were found at the first incident, and has suggested the noises may have been fireworks.

If you live close to Cortelyou and E 17th, have you heard shots or fireworks recently–and is there a regular time that it happens?