A father killed his wife, five children and his mother-in-law before turning the gun on himself, police said.
Michael Haight, 42, shot his wife Tausha, 40, weeks after she filed for divorce, officers in Utah said.
He is also thought to have killed their three daughters, aged 7, 12 and 17, their two sons aged, 4 and 7, and Mrs Haight’s mother Gail Earl, 78, on Wednesday before shooting himself.
Mrs Haight had filed for divorce from her husband on December 21 after 20 years of marriage.
Authorities had attended the property in recent years over a domestic disturbance, Jackson Ames, police chief in the city of Enoch, said yesterday.
Police have not confirmed that he was motivated by his wife’s divorce.
James Park, a lawyer who represented Mrs Haight in the divorce case, said she had not expressed any fear that her husband would physically hurt her.
Neighbours in the town of 8,000 gathered to pray and sing hymns outside the property yesterday.
President Joe Biden and First Lady Jill Biden said they are “mourning with the Enoch City, Utah community” after the “tragic shooting”.
The White House statement continued: “Less than one month after we marked 10 years since the Sandy Hook tragedy, another mass shooting has claimed the lives of five more children in Enoch City.”
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‘This community is hurting’
Neighbours said the family were active within the Mormon community and added they were “very welcoming”, KSL, a local news site, reported.
Mrs Haight’s sister-in-law Jennie Earl wrote on Facebook that she fought “incredibly hard” to be the children’s favourite aunt.
She added: “I pray that Christ’s love will mend our broken hearts and fill us with forgiveness and peace.”
Rob Dotson, city manager at the Enoch City Corporation, said: “Many of us have served with them in church, in the community and gone to school with these individuals.
“This community at this time is hurting. They’re feeling loss, they’re feeling pain and they have a lot of questions.”
The children’s local school district said that crisis intervention teams were available to students.
Iron County School District wrote: “We are saddened by the loss to our school community and will make every effort to help you and your child as needed.”