An off-duty NYPD sergeant was arrested in the Bronx following a scrape with his brother, police said.

Andy Rollins, 38, was taken into custody and charged with assault following an argument of “unknown origin” at 11:59 p.m. Friday, authorities said.

“It was a family fight,” an NYPD spokesman said, adding the victim suffered “bruises and scratches.”

The NYPD offered no other details.