A hit-and-run driver fatally struck a 31-year-old woman as she sprinted across the FDR Drive early Saturday — one of two fatal crashes to take place within just two hours, cops said.

The woman was crossing the northbound lanes of the FDR Drive on foot at about 12:15 a.m. when an oncoming black sedan rammed into her, cops said.

The fatal incident took place near the East Houston St. exit, police said.

Arriving first responders rushed the woman to Bellevue Hospital, but she couldn’t be saved. Her name was not immediately released as officials tracked down family members.

The driver of the sedan never stopped, police said. No arrests have been made.

About two hours later in the Bronx, a 31-year-old man died on the Throgs Neck Expressway near Pennyfield Ave. when the Mitsubishi he was driving slammed into a guardrail and an exit sign, cops said.

The driver was heading south on the expressway when he apparently lost control of the wheel and struck the guardrail, witnesses told police. He died at the scene.

The man’s name was not immediately released.