A Brooklyn man accused of gunning down the mother of his children as her own mother looked on in horror has been ordered held without bail.

Gabriel Rivera was arraigned Tuesday on charges of second-degree murder and criminal possession of a weapon for allegedly shooting ex-girlfriend Sade Sanchez five times in her neck, shoulder and torso late Sunday outside her Bushwick home.

Rivera, 26, surrendered to cops early Monday. Sanchez’s family told The Post that the estranged parents shared two boys, ages 3 and 6.

A day before she was killed, the 24-year-old allegedly called cops on Rivera, saying he assaulted her outside her Menahan Street home — on the same spot where she would later die.

The duo had a history of domestic disputes, according to law enforcement sources.

Rivera is due back in court Oct. 12. He faces up to life behind bars if convicted.