I asked Roosevelt Island Operating Corp (RIOC) Public Safety Department (PSD) Chief Kevin Brown and Communications Director Bryant Daniels today:

I understand that bullets were found on the sidewalk outside Roosevelt Landings several nights ago and were picked up by Public Safety Officers.

Is that true?

Are there any more details about this incident? Any statement from RIOC?

Mr Daniels answered:

At approximately 7:15 PM on May 9th, PSD was alerted to the presence of firearm ammunition on the ground in front of 560 Main Street. PSD immediately responded to the scene, found and recovered the lost ammunitionsix 9mm bulletsand notified the NYPD.

C&C cameras were then checked, and video was discovered of the ammunition falling out of an adult males duffle bag while he was entering the building. The individual was identified by PSD, and he is licensed to carry a firearm in New York. At approximately 7:40 PM, NYPD officers arrived and took custody of the ammunition.

C&C is the managing agent for the Roosevelt Landings 460 Main Street building.
The RIOC May 9 PSD Daily Blotter describes the incident as follow:

05/09/24 -1914 560 Main Street Suspicious Activity- PSD Responded Report Filed