An 18-year-old is due to appear in court charged with murdering his mother and siblings at a tower block in Luton.
Bedfordshire Police said it believed the victims were Juliana Prosper, 48; Kyle Prosper, 16, and Giselle Prosper, 13 - all of Leabank - but formal identification had not yet taken place.
Nicholas Prosper, also of Leabank, was due to attend Luton Magistrates' Court on Monday charged with their murders.
The defendant was also accused of a "number of firearms offences" relating to the incident on Friday morning, police said.
Floral tributes have been left outside the block in the Marsh Farm area of Luton where the bodies were found.
Officers were called to the flats at about 05:30 BST and found three people had been fatally injured.