DENVER (CBS4) – Two children were killed Wednesday morning in a shooting incident in a Northeast Denver home that claimed their mother’s life and left their sister critically injured.

The shooting left two children, Nevaeh and Eric, and their mother, Mayra Perez, dead in the 4900 block of Pearl Street.

Another child, Isabelle, who was injured survived and was rushed to the hospital. That child was listed in critical condition after surgery on Wednesday afternoon.

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According to Radio Reference, police could be heard speaking to dispatch about a father and child, “It looks like the father is hysterical, crying but says the 2-year-old is still breathing.”

Some family members told CBS4 they heard the incident was a murder-suicide, but that hasn’t been confirmed by police.

“She loved her kids so much that we can’t believe it,” Perez’s sister Sandra Nunez said by phone from Texas. “We loved her and she should have known, she should have known she had her family.”

Denver Police Lt. Matt Murray said officers are not searching for a gunman. Officers were awaiting a warrant to search the home for evidence Wednesday morning.

“It appears to be an isolated incident. We are talking to people, we are talking to witnesses but we have no indication that there is a shooter out there on the loose in Denver,” said Murray.

“All of the children appear to be under the age of 10. However because we have not been able to verify identity I can’t tell you exactly how old each child was,” said Murray. “They are young children.”

Emergency crews responded at approximately 6:55 a.m. to the house, which is located near the intersection with 49th and Pearl in the Globeville neighborhood.

They discovered the two children and their mother dead and one of the children hurt. Shortly after 7 a.m. an ambulance took what appeared to be a young person to a hospital. That person had been wheeled out of the house on a stretcher.

Police said the shooting was being investigated as a death investigation until more information becomes available.

Denver Police Chief Robert White said there are children involved in the incident, but wouldn’t elaborate. He said names and ages of the victims won’t be released pending notification of family members.

“I would ask that we all keep those involved — those that are going to be faced with this horrible tragedy — in our thoughts,” said White in a brief statement.

Nunez told CBS4 Perez and her husband moved their family to Colorado from Texas last year for the father’s construction job.

Neighbors said the family always seemed happy and had fun together.

“(I’d) see them outside playing with the kids, putting them in the water, in swimming pools. You would never know (something) was wrong,” neighbor Mike Mitchell said.

Police did say that no arrests have been made in the case.