Washington  - A US man was arrested in the murders of eight people, including seven of his relatives, nearly a week after he telephoned authorities to alert them to the killings.

Guy Heinze Jr, 22, was arrested Friday in the deaths at the family's mobile home at a trailer park in the south-eastern state of Georgia in Brunswick, a small city on the Atlantic coast, about 100 kilometres south of Savannah.

Heinze had placed an emergency call to authorities August 29, the day the killings occurred, saying, "My whole family's dead."

While police did not release the cause of deaths, Heinze said in his emergency call that it appeared as through they had been beaten to death.

He said in the call that he had arrived home after a night out to discover the bodies.

The victims were Heinze's father, aunt, uncle, four cousins and a cousin's boyfriend, police said. Her 3-year-old son survived and was hospitalized. The dead ranged in age from 15 to 49.

Heinze was also charged with attempted murder, lying to police and tampering with evidence.

Police were tight-lipped about the crimes, refusing to release details about why Heinze was arrested or a motive behind the killings. (dpa)