A woman who was stabbed in the neck while jogging on a Brooklyn bike path, as she prepared to run in the New York City marathon, has been declared brain dead, police sources said Saturday.

The 28-year-old runner was training on the waterfront near Bay Parkway and Cropsey Avenue in Bath Beach just after 8 p.m. when she was attacked, police said.

Disturbing images captured a blood-soaked scene along the pedestrian path.

Blood stains were seen on a railing that she likely grabbed onto and also on the concrete path, where what appears to be the her pink cell phone on the ground.

The woman, who’s identity has not yet been released, was found in the grass with a stab wound, the sources said.

She was rushed to Langone Hospital in critical condition, where she was declared brain dead, the sources said.

There were no arrests and police are canvassing for video, according to the sources.

While overall crime is down .5% in the local 62nd Precinct that covers the area, felony assault is up 17% as of Oct. 25, according to the most recent NYPD data available.

The TCM New York City Marathon is scheduled to kick off Sunday morning.