Six family members were dead in apparent murder-suicide in suburban Dallas after two brothers made a suicide pact that included the deaths of the other relatives, police said.
Allen police discovered the deaths after a concerned friend called police around 1 a.m. Monday worried that a person was suicidal, police Sgt. Jon Felty said.
"The two brothers had entered into an agreement that they were going to complete suicide, and from that, it went to where the entire family was taken with them," Felty said.
One of the brothers described in an Instagram post what occurred or would occur, Felty said.
One brother was 19 and the other was in his 20s, he said. The victims included a grandparent, two parents and a sister, he said.
Police identified the dead as father Towhidul Islam, 54; mother Iren Islam, 56; grandmother Altafun Nessa, 77; Tanvir Towhid, 21; and 19-year-old Farhan Towhid and his twin sister Farbin Towhid.
Neighbors told the NBC Dallas-Fort Worththey were stunned by the discovery. "The family is a very nice and happy family," friend Deelra Hassan said.
Police have had no substantive contact with the family, except for a call in 2018 about an unknown person who had rung their doorbell, Felty said. He said that evidence suggests the killings happened on Saturday.
Felty said the family is from Bangladesh, and investigators found some family members in Florida, who were en route to Texas.
"We have never had an incident like this in the 21 years that I have been here," Felty said. "... It's just a tragedy. There's no other way to describe it. It's a tragedy that you just can't imagine."
The police investigation was ongoing Monday.
The letter posted to social media said the brothers planned to fatally shoot their family members and then themselves, and it mentioned being clinically depressed, NBC Dallas-Fort Worth reported.
Allen is a suburban city of around 105,000 north of Dallas.
If you or someone you know is at risk of suicide please call the U.S. National Suicide Prevention Lifeline at 800-273-8255, text TALK to 741741 or visit SpeakingOfSuicide.com/resources for additional resources.