BROKEN ARROW, Okla., July 24 (UPI) -- Two teenage brothers were taken into custody by Oklahoma authorities Thursday and accused of murdering their parents and three young siblings -- as well as severely wounding a fourth.
The attacks occurred at the family's home in the town of Broken Arrow, a suburb of Tulsa, late Wednesday night, officials said. About 30 minutes before midnight, the brothers allegedly stabbed all five family members to death. Authorities say a fourth sibling, a 13-year-old girl, sustained serious injuries.
A fifth sibling, a two-year-old girl, was not harmed in the attack.
Police responded to the home after a 911 dispatcher received a phone call from the home, during which no one spoke. Investigators believe the emergency call was made by the injured girl. When officers arrived, they supposedly found Robert Bever, 18, and his 16-year-old brother hiding in woods behind the house.
Both boys were arrested without incident, police said.
"I don't know that we as rational people can understand how you could have a motive to kill the people that raised you and your siblings," Broken Arrow, Okla., Police Cpl. Leon Calhoun said.
Killed in the attack were the suspects' parents, David and April Bever, ages 52 and 44, and three siblings -- two boys and a girl, ages 12, 7 and 5, respectively, officials said. The names of the dead children and the 16-year-old suspect were not released because they are juveniles.
The teens used "blade type" weapons to attack the family, including a hatchet, the New York Times reported.
The injured girl underwent surgery and was last listed in serious but stable condition, according to authorities. She and the toddler were taken into protective custody.
According to statistics, Tulsa sees an average of fewer than one murder a year. Calhoun told CBS News that a quintuple murder such as this "isn't just unusual, it's unheard of."
Broken Arrow, a town of about 100,000 people, was listed as one of the United States' safest cities not long ago -- based on FBI crime statistics