Jansen Michael Hudgens, 44, reportedly killed his wife, local attorney Marla Jordan Hudgens, 40, as well as his 3-year-old son Christopher and 6-month-old twins Gwen and Faye, according to Phoenix police.
Police were first called to the home around 8am local time on Wednesday "regarding an unresponsive person inside the house with a strong odour of gas."
"The Haz Mat teams entered the home and found multiple victims deceased," the police said in a statement.
Open propane tanks were found inside the home, and a gas line was found in the home that was not attached to any appliances.
Police determined that gas levels inside the home were safe and did not pose a threat to neighbours before they began their investigation of the deaths.
"Once inside, detectives discovered the bodies of two adults and three children from what are believed to be members of the same family. The bodies had obvious signs of trauma," police said. "Support services were offered to the neighbors of this tight-knit neighborhood and those associated with the victims."
No official motive has been released by police, but neighbours speaking with AZFamily said the couple’s marriage had become strained.
According to Ms Hudgens friend, Brett Hagerty, she was seeking to end the couple’s marriage, but none of her friends assumed that she could have been in danger.
"We never had any indication from her that she felt scared or threatened or unsafe," he said.
Another friend, Khanh Andersen, told the outlet that Ms Hudgens’ sister had died as a result of suicide two months prior. She noted that the sister’s "celebration of life" event was held only a week ago and claimed that Mr Hudgens did not attend.
Police described the scene as a "complete tragedy."
“Not only is this devastating to the first responders that had to respond and witness what’s inside, but this neighbourhood is very close-knit including the extended loved ones and family members that are related to this home and this residence,” Sgt Melissa Soliz of the Phoenix Police Department said.
Police said “obvious signs of trauma” were present on all the victims. A cause of death has not yet been released.
Kevin Van Winkle Jr, a managing partner of Lewis Roca, the firm where Ms Hudgens worked, remembered the woman fondly.
“We are overwhelmed with grief at the loss of our friend, colleague and partner, Marla Hudgens, and her family. We are in complete shock and are only just beginning to process this awful tragedy," he wrote. "Marla was a passionate lawyer and advocate for her clients. She was an equally passionate leader who worked tirelessly to make our firm a better place. But more than that, Marla was a loving mother and loyal friend. The impact of this loss on the community and on our firm is immeasurable.”