An off-duty police officer returned to her Queens home Sunday night to find that a thief had broken in and stolen her service weapon, sources said.

The 35-year-old officer was about to enter the front door of her Flushing home when she noticed the inside chain was secured from the inside around 10 p.m.

The woman forced the door open to find her home had been ransacked and her Glock 19 9mm pistol had been stolen, along with some other personal property. It’s believed the thief gained entry to the home through an open window, sources said.

The NYPD’s Internal Affairs Bureau in investigating the incident.