STOCKHOLM, Aug 26 (Reuters) - Swedish prosecutors have apprehended a second person suspected of involvement in last week's attack at a school in which a 17-year-old girl was killed and three people were injured by a man wielding a sword, they said on Wednesday.
On Friday, police arrested an 18-year-old man they said was believed to have carried out the attack at the Brinell high school in the central Swedish town of Fagersta, and launched an extensive investigation.
The second man was held on suspicion of accessory to murder and accessory to attempted murder, and a decision will be made on Thursday on whether to ask a court to formally detain him, the prosecution authority said in a statement on Wednesday.
The agency did not say how the second suspect may have aided the attacker.
A source on Saturday said police were investigating whether the 18-year-old attacker was involved in online communities promoting school violence.
(Reporting by Anna Ringstrom; Editing by Terje Solsvik and Conor Humphries)
