A teenage boy in New Mexico has been arrested in connection with the fatal shootings of five people.
Two adults and three children were found dead with apparent multiple gunshot wounds at a house near Albuquerque on Saturday evening.
Bernalillo County sheriff's spokesman Aaron Williamson said it was not yet clear what the suspect's motive was, or his connection to the victims.
He faces two counts of murder and three of child abuse resulting in death.
Mr Williamson said they were trying to identify if the victims were related.
The authorities have not released the name or age of the suspect, although local media reported that he was aged 15.
Investigators are also trying to determine who owns a number of guns that were found at the home, including a semi-automatic military-style rifle, the Associated Press news agency reports.
The shooting came hours after pro-gun activists staged rallies across the United States to demonstrate against stricter gun control laws.
President Barack Obama has pledged a raft of measures to tighten gun laws following the mass shooting at a school in Newtown, Connecticut, in mid-December that killed 20 children and six adults.