A crazed father butchered his wife and daughter with a massive curved dagger before he was shot dead by cops as he was trying to kill another relative in their Virginia home, authorities said.

Chhatra Thapa, 54, went on the sickening stabbing frenzy inside the family’s Fairfax home just after 5 a.m. Monday as his 1-year-old grandson was also inside.

“To describe this scene as bloody would be an understatement,” Fairfax County Police Chief Kevin Davis told a press conference.

“The damage and the chaos and the carnage that was perpetrated by this man in his 50s on his own family is unimaginable.”

Officers rushed to the scene to reports of a domestic violence assault and found Thapa’s wife, Binda Thapa, 52, and their 33-year-old daughter, Mamta Thapa, suffering from multiple stab wounds.

The crazed dad was in the middle of knifing his son-in-law when cops stormed in.

Police opened fire, killing Thapa, after he repeatedly refused to drop the huge blade, authorities said.

The giant, blood-soaked knife was found alongside his body.

Binda and Mamta were later pronounced dead at the hospital. The son-in-law remains hospitalized after being rushed there in life-threatening condition.

The killer’s 1-year-old grandson was found unharmed inside the home in the wake of the bloodshed.

Thapa, meanwhile, died at the scene, according to police.

It wasn’t immediately clear what led up to the stabbing frenzy.

The son-in-law told cops that he’d been outside shoveling snow when he heard some type of disturbance.

He rushed back inside and call 911 after seeing his wife had been stabbed.