A woman was saved from a predawn sex assault on the Christopher Street PATH platform Sunday when a security officer saw it unfold on a surveillance camera — and demanded over a loudspeaker that the attacker stop.

The stunned man complied, halting his attack on the 31-year-old victim at about 4:45 a.m.

The same PATH Security Operations officer quickly summoned Port Authority police, and the suspect, Andres Rodriguez, 33, of Hackensack, was arrested.

The woman was treated at an area hospital.