Police identified the man allegedly behind the wheel of the 2018 Honda as Holtsville resident William Schultz.
Investigators said the 67-year-old was driving westbound on Montauk Highway when he struck the girl as he made a right onto First Avenue around 6 p.m.
The girl suffered a broken wrist, according to court documents and was taken to the hospital.
News 12's Jonathan Gordon was at 1st District Court Tuesday morning.
Investigators said off-duty Nassau County Police Officer Ryan O'Leary was the first on the scene and detained Schultz until Suffolk County police patrol units arrived.
Schultz told police, "I drank one wine," and had bloodshot, glassy eyes, a strong odor of alcohol on his breath, poor coordination and slurred speech, according to court documents.
He failed the field sobriety test, but declined to take a breathalyzer, according to court paperwork.
Suffolk County police arrested Schultz and charged him with DWI, failure to stop and a license plate violation, according to online court records.
Schultz was released following his arraignment. His next court appearance is scheduled for Thursday, Oct. 22.
News 12 reached out to Nassau County police for more information about the off-duty officer who responded, but has not yet heard back.