A deranged man fatally stabbed his mother inside her Brooklyn home, police sources said.

Ingham Scarder, 24, was arguing with Alfonette Scarder, 47, inside her Flatbush apartment on St. Paul’s Place at about 11:00 p.m. Wednesday when he whipped out a knife and viciously stabbed her, police sources said.

Police, responding to reports of an assault, made the gruesome discovery and found the assailant still lingering inside, police said. The victim was rushed to Kings County Hospital where she later died.

Scarder who suffers from bipolar disorder, was arrested inside the apartment, police sources said. He has been charged with murder and criminal possession of a weapon.