It happened just after 6:30 p.m. near East 113th Street and 1st Avenue.
The child was sexually assaulted by two unidentified males who then ran away in an unknown direction.
On Tuesday, NYPD officers released photos of the two men they are looking for in connection to the crime.
Residents in the neighborhood said they were very upset that this happened to a girl so young.
"This neighborhood is not one of the best neighborhoods but it looks like a lot of bad things are happening now in the summertime and it is sickening," one resident said. "Twelve years old, I have kids and I have grandkids, and that is something that you can't even explain to a parent."
Anyone with information is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).
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