A Phoenix woman has been arrested on suspicion of killing her three children, who were found dead inside the family's home, authorities said Tuesday.

The 22-year-old mother, Rachel Henry, “has admitted to harming her three children, which caused their demise,” police Sgt. Mercedes Fortune told reporters outside the home on a block with an old mobile home, several weathered wooden houses and other buildings in a once rural area of southern Phoenix.

Police said there was no obvious trauma to the 7-month-old girl, 2-year-old girl and 3-year-old boy and that it's too early to determine how the children died. Relatives initially believed illness may have been a factor.

A makeshift memorial is set up near a home where a Phoenix woman was arrested on suspicion of killing her three children after they were found dead inside the family home Tuesday, Jan. 21, 2020, in Phoenix. (AP PhotoRoss D. Franklin)

A makeshift memorial is set up near a home where a Phoenix woman was arrested on suspicion of killing her three children after they were found dead inside the family home Tuesday, Jan. 21, 2020, in Phoenix. (AP PhotoRoss D. Franklin)

“We are comfortable in saying now that the mother is responsible for the death of the children,” Fortune said.

A relative who lives at the house called police late Monday, and officers found the children in a living room, authorities said.

Officers administered CPR and fire officials provided first aid, but the children were pronounced dead.

Police were interviewing the 30-year-old father and a 49-year-old relative who lives in the home, authorities said. The family had recently moved to the area from Oklahoma.

Henry has been booked into jail on three counts of first-degree murder, police said. There was no information on whether she had an attorney who could speak on her behalf.

The family lives in a neighborhood with old homes of wood or stucco, where a white Spanish-style church graces a corner. But there is new construction going up all around, with a golf course and several housing developments of single-family homes priced at more than $500,000.