An Arizona man went on a killing rampage Tuesday – all because he didn't like the dogs in his neighborhood.

According to the Associated Press, 56-year-old Michael Guzzo shot and killed four members of a central Phoenix family and their two dogs before going home and killing himself. Although his motifs can't be proven, neighbors say that Guzzo hated the noise of their barking dogs, which could have led him to kill the family.

The man worked as a third shift pharmacist, so when the dogs would bark during the day, he would get extremely angry when he was woken up by them. Guzzo also went door to door asking neighbors to quiet their dogs and even put up fliers around the neighborhood reminding people about ordinances and threatening to report people for fines.

Guzzo killed his neighbor Bruce Moore, 66, along with his daughter, Renee Moore, 36, her husband, Michael Moore, 42, and her son, Shannon Moore, 17, as well as their two dogs.

Neighbor Barry Hatchett witnessed the shooting, and told KNXV-TV, “When I walked outside, I saw a middle aged gentleman with a big shotgun in his hand, had it thrown over his shoulder actually. And then he spoke to someone across the way. And what he said was, 'You didn’t think I seen you home boy?' Then he pumped the gun and he shot it.”

The Daily Mail reports that Guzzo also attempted to kill others in the neighborhood. He went to the home of Libni DeLeon, knocked on the door, and shot twice through the door. DeLeon did not answer, and he was not injured.

Guzzo's ex-wife of over ten years, Janet Guzzo, said Guzzo suffered from paranoia, anger and depression. "I always thought it was just a matter of time, but I thought it would be a quiet thing, he'd take himself out in his own home," she said. "I never thought he would go out in a blaze of glory and kill a whole family ... He was just so tortured."

Guzzo wouldn't seek help for his anger issues. "He had this perception that there was nothing wrong with him. He thought, 'They're all out to get me,'" his ex-wife said. "I believe as he got older, the demons got worse."