Arrest hearings against the three teenagers took place on Wednesday.
At lunchtime, the Gävle district court announced that the 15-year-old and the 17-year-old were detained.
During the afternoon, the decision was made to also arrest the 16-year-old.
The three teenage suspects deny any crime and want the court to take their young age into account.
According to the court, however, there are special reasons for detention despite their young age.
Known to the police from before
The 15- and 16-year-olds are from Gävle.
The 16-year-old figures in the criminal investigation after the attempted murder in Forsbacka last year, where the police connect him with a criminal group in Gävle.
The 17-year-old lived in Sätra in Gävle until this summer, but is now registered in Skåne.
He was convicted last year of theft.
Just the beginning for the prosecutor
Whether the evidence is strong enough already now to be able to lead to a future indictment is unclear, according to chamber prosecutor Therese Stensson Jonsson.
- There is an incredible amount that remains.
I would say that we are in the initial stages of the investigation now, she says.
Hear the prosecutor's thoughts on the case in the clip.