A New Jersey man stabbed his elderly mother multiple times and left her bleeding on the sidewalk — then refused to open the door when cops came to arrest him, forcing the lockdown of a nearby school.

An off-duty corrections officer found the 60-year-old woman on Fairview Avenue in South River with stab wounds around 2:30 p.m., The Star-Ledger reported.

When police arrived, Kazufumi Nakatani, 33, wouldn’t let them inside his mother’s home, and cops had to call in the Middlesex County Special Operations Team to get in.

South River Public Schools were on lock-down during the standoff, which lasted about an hour.

Nakatani was arrested and charged with attempted murder and possession of a weapon.