Nicholas Prosper, 18, is charged with the murders of a woman and two teenagers in a flat in Luton.
An 18-year-old man has been charged with murder after three people were found dead in a tower block in Luton on Friday.
Nicholas Prosper, of Leabank, was arrested on Friday morning after the bodies of a woman and two teenagers were discovered at a flat.
Bedfordshire Police said the victims were believed to be Juliana Prosper, 48, Kyle Prosper, 16, and Giselle Prosper, 13 – all also of Leabank – but formal identification is yet to take place.
The suspect, who has also been charged with a number of firearm offences, is due to appear at Luton Magistrates’ Court on 16 September.
Officers were called to the Leabank block of flats, in the Marsh Farm area of Luton, at around 05:30 BST on Friday and found three people with fatal injuries.
Bedfordshire Police said the 18-year-old was arrested shortly after officers were called to the property.
A firearm was found during a search of the surrounding area, the force confirmed.
Det Supt Rob Hall, from the region’s major crime unit, said officers who arrived at the scene were “met with such awful circumstances”.
He continued: “First and foremost our thoughts are with the three people who sadly lost their lives yesterday and their loved ones.
“Although formal identification has yet to take place, next of kin of those who we believe to have died have been informed and are being supported by specialist officers.
“We would ask that their privacy is respected at this unimaginably difficult time.”
He added that officers would remain at the tower block while the investigation continues.