A 42-year-old Texas woman, Colleen Nichole Lemmon, has been charged with two counts of capital murder after authorities said she shot her two sons inside their home in Waxahachie, Texas.

The victims were identified as 21-year-old Christopher Scott Pitre and his 15-year-old younger brother.

According to the Ellis County Sheriff’s Office, deputies were called to a house on Big Sky Drive shortly before 4:15 a.m. on Thursday following a report of an “unknown emergency”.

When deputies arrived, they found both brothers with gunshot wounds inside the house.

Christopher was pronounced dead at the scene. His younger brother was taken to hospital in critical condition but later died from his injuries.

Lemmon was also found injured at the scene and was taken to hospital for treatment.

An arrest affidavit cited by local reports said Lemmon was covered in blood and had what appeared to be self-inflicted cuts on her wrists. A handgun was also found nearby.

Investigators said evidence recovered from the house gave them probable cause to believe Lemmon had shot both boys.

According to the affidavit, Lemmon allegedly told responding officers: “I shot both my kids.”

She was later arrested and charged with two counts of capital murder.

The boys’ father, Scott Pitre, said his younger son had only recently celebrated his 15th birthday. He said he wants justice for his children.

A neighbour, Ida Brown, described the deaths as heartbreaking and said she was praying for the family.

Ellis County Sheriff Brad Norman also offered condolences to the victims’ relatives.

“My deepest sympathies go out to the victims’ father, family members, and loved ones involved in this tragic incident,” Norman said.

“They will remain in our prayers during this difficult time.”

Lemmon is being held on a $2.5 million bond.

Authorities have not disclosed a motive for the killings.