TYRONE, Mo. — A man who authorities say may have been unhinged by the death of his ailing mother killed seven people and then took his own life in a house-to-house shooting rampage that wiped out a swath of this tiny town in the Missouri Ozarks.

Joseph Jesse Aldridge, 36, carried out the killings with a .45-caliber handgun Thursday night or early Friday at four homes in Tyrone, the no-stoplight community of about 50 people where he lived with his mother, the Missouri State Highway Patrol said.

Aldridge was found dead of a self-inflicted gunshot wound before dawn in a idling pickup truck in the middle of a highway 15 or 20 miles away.

The patrol said four of the dead – two couples – were cousins of Aldridge’s, ranging in age from 47 to 52. The names of the rest of the dead – and an eighth victim who was wounded but expected to survive – were being withheld until relatives could be notified.

All the victims were adults and were gunned down within a few miles of one another.

Authorities said the motive was unclear and no suicide note was found. But as the investigation unfolded, they found Aldridge’s 74-year-old mother dead, apparently of natural causes, on a couch at her home, officials said.

She had been under a doctor’s care and appeared to have been dead at least 24 hours, Texas County Coroner Tom Whittaker told the St. Louis Post-Dispatch.

Whittaker speculated that the son “came home and found her deceased and then for whatever reason went on a rampage and started killing people.”

Around town, Aldridge was described as a recluse, and it was unclear what, if anything, he did for a living.

The killings traumatized Tyrone, a town about 40 miles from the Arkansas line.

The sheriff’s office learned of the attack when it got a call about 10:15 p.m. Thursday from a young woman who said she had fled to a neighbor’s home after hearing gunshots in her house.

The neighbor, who refused to give his name, said the teenager “was crying so hard, but I finally got out of her ‘My mom and dad have been shot.’ “