Ellen Meany, 45, was riding southbound, against traffic, in a northbound lane of Unqua Road near Morris Lane when she accidentally banged into the mirror of a parked car and fell off her bike, police said.
Meany landed on the roadway and was struck by what appeared to be an older model, teal-colored Ford Taurus, police said.
The driver continued on, leaving the scene without stopping to report the accident, police said.
The accident, which occurred about 11:35 a.m., is near the Unqua Elementary School, which Meany's children attend, homicide detectives said. It was unclear how many children Meany has and who attends the school.
Meany was airlifted to Nassau University Medical Center and was in critical condition Thursday night, police said. "Our concern, clearly, was that it was in close proximity to a school," Massapequa school district Superintendent Charles V. Sulc said. "God forbid it was earlier in the day or later in the day, and a child was out there crossing."
The road was closed until shortly before 3 p.m. as police conducted a crime scene investigation, Sulc said: "We had to put a contingency plan in place in case it was still closed at the end of the school day."
It reopened before school ended, he said.
Detectives ask anyone with information to call Crime Stoppers at 800-244-TIPS. All calls are confidential. Police have also released a Crime Stopper flier.
With John Valenti