DALLAS (AP) — Authorities have identified six people found dead in a suburban Dallas home in what police said was an apparent murder-suicide plot.

The Allen Police Department said investigators believe brothers Tanvir Towhid, 21, and Farhan Towhid, 19, made a pact to kill their parents, sister and grandmother before killing themselves. The bodies were found early Monday by officers performing a welfare check, Sgt. Jon Felty said.

“It appears that the two brothers had entered into an agreement,” Felty said.

The victims were identified as Altafun Nessa, 77; Iren Islam, 56; Towhidul Islam, 54; and Farbin Towhid, 19.

Felty said one of the brothers wrote a lengthy post on social media in which he said he and his brother had a plan to kill their family members and then themselves. He also wrote that all of his decisions were based on weighing pros and cons, including the decision to kill his family.

The Dallas Morning News reported that Farhan Towhid posted the a link to the letter on Instagram but the account has since been disabled.

Several members of the Bangladesh Association of North Texas gathered near the home Monday after news of the family’s death was released, the newspaper reported. Ahmad Hossain, who lives about a block away, told the newspaper that the family moved to the area about seven or eight years ago from New York.

Hossain said Nessa, the grandmother, was visiting the family from Bangladesh. He said she was scheduled to return home last week but couldn’t because of the COVID-19 pandemic.

Fazia Rahman, who graduated from Allen High School last year with Farhan and Farbin Towhid, said the family was welcoming and the parents “treated everyone like they were their own kids.”

“We don’t want this to be their family legacy,” she said. “They were such great people, they genuinely touched the lives of everyone who they came in contact with. … They were good people who had bright futures ahead of them.”