A Florida mom and her son were shot and killed by her ex-husband during an argument that began over an electric bill and lights left on in the house.

According to NBC News, Michael Williams, 47, was arrested on Sunday night and charged with two counts of first-degree murder. The Volusia Sheriff's Office identified the victims as Marsha Ebanks-Williams, 48; and Robert Adams, 28.

The sheriff's office said Williams called 911 just before 8 p.m. and told the police that he shot the victims "in self-defense" at the DeLand home that he was sharing with her ex-wife following their June divorce that ended their 10 years of marriage.

Officers responded to the Daytona Park Estates neighborhood's home and found Williams in a vehicle parked in the driveway. The sheriff's office noted that Williams surrendered while the Florida mom and her son were found dead inside the home.

There were also two young children inside the house, ages five and six, who were identified as Adams' children. Police said the children were visiting their father from Tallahassee and may have witnessed the shooting.

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Florida Mom, Son Killed by Ex-Husband Over Electricity Bill

Michael Williams told police that he had shut off power to the house, locked the electrical panel, and left. When he returned to the home, the Florida man discovered that the lock had been cut and replaced, and the power to the house had been restored, People reported.

Police said that incident led to the argument that resulted in Williams fatally shooting his ex-wife and stepson. According to Williams, the Florida mom and her son attacked and punched him repeatedly in the face.

However, police noted that Williams did not appear to have any injuries "other than some superficial scratches." Chief Deputy Brian Henderson said investigators determined that Williams went berserk over arguments he had with his ex-wife over electricity in the home.

He noted that Williams was upset that he felt that the two were leaving the lights on in the house, which prompted him to put a lock on the box outside of the house.

Henderson held up a mugshot of Williams in a news conference, saying "this does not look like a violent attack to me that warrants being shot multiple times."

Young Children Likely See Suspect Shooting Florida Mom, Their Father 

Brian Henderson said the five and six-year-old children seemed to have witnessed their father and grandmother getting murdered, adding that it was a senseless murder that did not have to happen, New York Post reported.

The exes lived together after the divorce and had planned to sell the property and split the proceeds. The only weapon found on the property was Michael Williams' gun.

Police officers reportedly responded to five domestic disputes at their home in the past year. However, there were no allegations of violence at the time. Authorities noted that Williams' criminal record includes allegations of child abuse, domestic violence, and battery on a law enforcement officer.

Henderson called the relationship toxic and revealed that the Florida mom called the sheriff's office just hours before the attack, seeking legal advice. Williams is being held in the Volusia County Branch Jail with no bond.

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This article is owned by Latin Post.

Written by: Mary Webber

WATCH: Florida Man Accused of Shooting, Killing Ex-Wife, Her Son Over Electricity Usage - From FOX 35 Orlando