An Arizona grandmother is facing murder charges after investigators said she killed her twin 8-year-old grandsons who had autism.

According to the Pima County Sheriff's Department, Dorothy Flood, 55, was arrested Friday and charged with two counts of first-degree murder in the fatal shootings of Jaden and Jorden Webb.

>> See photos of the children here

Authorities said they found Flood unresponsive and the boys dead Thursday afternoon while responding to a medical call at a Tucson home. Flood, the twins' guardian, "had symptoms of an apparent overdose and was transported to a local hospital," the Sheriff's Department said.

>> See the Sheriff's Department's Facebook post here

In court documents obtained Monday by KOLD-TV, investigators said Flood "admitted to shooting both of her grandchildren twice each, then attempting to kill herself by taking an unknown quantity of prescription medication."

She was jailed on $250,000 bond, KOLD reported.

>> Read more trending news

According to friends of the family, the boys' mother, Kristen Webb, killed herself two years ago, KOLD reported. Since her death, Flood had been taking care of the twins, who had autism, friends told the news station.

Read more here or here.