Phoenix Shooting Rampage: Barking may have led to massacre that left neighbors, dogs, gunman dead, police say

(CBS/AP) - Loud barking may have sparked a shooting rampage that left five people - including four members of one family - and two dogs dead at a central Phoenix townhouse Saturday, police said. Police identified the suspected gunman as Michael Guzzo, 56, a next-door neighbor to the victims.

Guzzo died of a self-inflicted gunshot wound after apparent massacre, police said.

Phoenix police Sgt. Tommy Thompson said there is "some indication" that barking "perhaps was a problem." But he added that because of the deaths, a motive may never be known.

Police identified the victims as Bruce Moore, 66; his daughter, Renee Moore, 36; her husband, who took his wife's name, Michael Moore, 42; and Renee's son, Shannon Moore, 17.

After shooting the family members and dogs, police said Guzzo walked across the courtyard and shot through a door and window of another townhome in the complex, CBS affiliate KPHO reports. No one in the second townhome was hurt, police said.

Guzzo left the scene on foot, apparently returning to his home, reports the station.

When police responded to the victims' home, they discovered two bodies on the patio and two inside, reports KPHO. Two dead dogs were also discovered with gunshot wounds.

Guzzo's body was discovered in a townhome next door to where the family was found, police told KPHO.

Police said they found a pump shotgun, apparently the weapon used in the killings, next to his body. Thompson said there was no indication Guzzo had a violent past.