Eight people are dead and one person has been injured after a series of shootings in south-central Missouri.
Police made the discoveries on late Thursday at five different homes in or near the small town of Tyrone after an emergency call.
Officials found Joseph Jesse Aldridge, 36, dead of a self-inflicted gun wound in a vehicle near one of the crime scenes.
At least four of the victims have been identified as his family members.
Police are continuing to investigate Aldridge's motive.
Residents reported that police went door-to-door on Friday warning them to secure their homes.
On Friday afternoon, police identified four of the dead as Garold Aldridge, his wife Julie Ann Aldridge, Harold Aldridge and his wife Janell.
They were cousins of the gunman, police said. Joseph Aldridge's mother, Alice, was found dead of natural causes in the course of the investigation.
All the family members lived within three sq miles (5 sq km) of each other, police said.
Around 22:15 local time (4:15 GMT) on Thursday, officers from the Texas County Sheriff's Department responded to an emergency call from a young woman claiming she heard gunshots in a home.
Police found two people dead in the house.
As they continued searching, they found six others dead and one injured across four other residences.
"This is a horrific tragedy, and our hearts go out to the victims of these senseless acts and their families," Missouri Governor Jay Nixon said in a statement.
Aldridge was discovered in vehicle in nearby Shannon County. He died of an apparent self-inflicted gunshot wound.
Texas County Coroner Tom Whittaker told The St Louis Post-Dispatch newspaper his mother had been found dead at her home, apparently of natural causes.
She had been under a doctor's care and appeared to have been dead for at least 24 hours, Mr Whittaker told the newspaper, adding all the victims were adults.
Authorities took the injured victim to a nearby hospital. They will not be identifying the three other victims until their next-of-kin has been notified.
Residents of the rural area were in shock.
"We've never had anything of this magnitude before," said County Clerk Don Troutman, a resident of 36 years.
Scott Dill, superintendent of the school district that serves Tyrone, said the community was "holding our breath...to find out specifics".
"We want to help people make sense of this tragedy," he said.