On Tuesday, police found Farman Sherwani, his wife Layla Sherwani, and their sons Mateen Sherwani, two, and Shaheen Sherwani, 12, dead after conducting a welfare check at the house, according to NBC News.
Police then learned from the Islamic Association of Allen — the group that identified the bodies — that the family had lost a four-year-old girl to drowning just three weeks before the apparent murder-suicide.
Jonathan Maness of the Allen Police Department told NBC News in an email that the child's drowning "is believed to be a factor" that lead to the tragedy.
Police were called out to the house after another resident found themselves locked out for two hours and could not contact the others inside.
"After other family members arrived at the house, police gained access and found four people dead," the police department said in a statement.
The Islamic Association of Allen held a prayer vigil for the family on Tuesday, which was highly attended by mourning community members.
"We are deeply saddened by the news of the passing of four family members," the association said in a statement.
The centre's leader, Abdul Rahman Bashir, said it had been a "very heavy day" for his community.
"Waking up to the news of losing a four member family all of a sudden is not something that anyone can be prepared for, family members or let alone anyone in the community, so it's been a very heavy day for everyone in the community," he told NBC Dallas Fort Worth.
He said he was aware that the family had recently lost a daughter to drowning.
"As the father of three children myself, it's something very hard to digest and grapple with the gravity of the situation, what the family may have been going through," he said. "We just continue to encourage the community to be there for each other during this time of sorrow and grief and we also encourage the community to cherish their family members and the moments that they have and be cognizant of the uncertainty of life."
Neighbours expressed their condolences for the family to the broadcaster.
"It was just really sad and hard and all of us felt for the family as we were watching them mourn in the front yard," Jacqueline Soto, a neighbour who lives across the street from the residence, said.
Allen Independent School District sent a letter to parents announcing that a fifth grader at the school had died. The school confirmed to the broadcaster that the letter was related to the ongoing investigation, and said it was making counseling available for students.