Chief Geier said officers pulled the three victims from the warehouse and rendered aid before they were taken to UNM Hospital. One of those victims has been upgraded to stable condition. The others are still in critical condition.

"Fortunately, they're all clinically improving," said Stephen Lu, director of emergency general surgery at UNM Hospital. "We hope that continues and everyone at UNMH is working overtime to the best of their abilities to make sure they do as well as possible."

Chief Geier said all indications point to the shooting being spontaneous. However, he said a promotional issue has been brought to the department's attention. He also said Melton may have had mental health issues and used drugs prior to the shooting.

Melton had no criminal history, according to Chief Geier.

"I think one traffic accident out of Rio Rancho but no criminal history, nothing that would indicate that we could have prevented this or had advanced information," Geier said.

A handgun was recovered at the scene of the crime. Police are looking into whether Melton purchased the gun legally.

Tuesday afternoon, police went through a home on Osage Pl SW, where neighbors say Melton lived.

"Very shocking to hear someone as quiet as him would do something like this," said Loretta Baca. "He always just went in the house, never talked to anybody in the neighborhood. Very quiet. Nice young man, as far as I could see."

Officers were seen removing multiple rifles from the home. Police also plan on searching Melton's vehicle for evidence.