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A 33-year-old man killed his mother and the family dog at the home where he lived with his aunt and uncle in Simi Valley, then left a message indicating there was a bomb in his bedroom before killing himself, police said Friday.

Michael John Cullen and his mother Esperanza Guadalupe Cullen, 58, of Las Vegas were found dead in the home, along with the dog, Simi Valley police announced a day after the situation prompted an evacuation of surrounding homes.

Michael John Cullen, left, and his mother Esperanza Guadalupe Cullen are shown in photos released Nov. 8, 2019, by Simi Valley police.
Michael John Cullen, left, and his mother Esperanza Guadalupe Cullen are shown in photos released Nov. 8, 2019, by Simi Valley police.

When Michael Cullen’s uncle came home after work Thursday evening, he found an unidentified woman lying in a pool of blood in his kitchen.

Officers responded to the home — on the 500 block of Fairfield Road, in a gated section of the Wood Ranch community — and determined the woman was dead. Meanwhile, the uncle noticed a message written on Michael Cullen’s bedroom door.

It read, “bomb inside don’t open explosion,” police said.

The uncle and officers immediately left the house out of concern there was indeed a bomb inside. Nearly 50 residents were evacuated from nearby homes.

A bomb squad, K-9 unit, SWAT team and crisis negotiators were called to the home. Eventually a robot was sent in, and the younger Cullen was found inside his bedroom, dead of an apparently self-inflicted gunshot wound. A bomb was not found.

Cullen’s mother and the dog also had gunshot wounds, police Cmdr. Steve Shorts said.

He described it as a “pretty graphic or bloody scene.”

He told the Associated Press that it appears the mother was visiting when the gunman shot her and the dog before turning the gun on himself.

Police believe the son had a dispute with his mother that prompted him to kill her, the dog and then himself. It’s not clear what the dispute was about.

There aren’t any more victims or suspects, police said.

KTLA’s Alexis Lewis contributed to this story.