One of the brothers accused of trying to kill his parents had been planning to murder them since he was just 11, police said.

Cameron Ervin, 17, and his 22-year-old brother Christopher are accused of brutally attacking their parents, Yvonne and Zachary Ervin, at their Atlanta-area home on September 5.

Read: Mom Attacked by 2 Sons Begs for Help in Chilling 911 Call: 'My Children Are Trying to Kill Me'

As the brothers spoke to police afterwards, "one of the sons… stated that he had been planning this since he was eleven years old," according to a search warrant that was released on Monday and cited by the Atlanta Journal Constitution. It is not clear which brother made the claim.

The sons had reportedly called their parents to ask if they could make them dinner and police believe they then spiked the couple's drinks with Xanax. Yvonne was strangled and badly beaten, while Zachary was stabbed multiple times.

Following the attack, the sons admitted to "attempting to set the residence on fire, strangling their parents with a pillow and/or plastic bag, and stabbing the father," according to the search warrant.

A terrifying 911 obtained by INSIDE EDITION revealed the terrifying scene.

Yvonne, 50, told the 911 operator: “They're trying to strangle and shoot us. They put Xanax in our food. They thought we were asleep and they tried to attack us. They beat me up. They beat him up. They're trying to kill us."

She continued: “I don't know why they've done this, I really don't. I guess they want the insurance money, I’m not sure.”

A motive for the attack is still unclear, police said.

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The brothers are being held in the Gwinnett County jail, each charged with two counts of aggravated assault and first-degree arson.

They waived their probable cause hearing in Gwinnett magistrate court and are being held without bond.

Their parents have been released from hospital.

Watch Below: Family of Teen Who Killed His Parents Says He Deserves His Punishment

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