People leave flowers and candles at a makeshift memorial outside a school, one day after an attack carried out by a teen with a sword in Fagersta, Sweden, Saturday. A 17-year-old girl was killed and three others were injured at the school after the attack Friday. Photo by Magnus Lejhall/EPA

Aug. 22 (UPI) -- A 17-year-old girl is dead after a sword attack at a Swedish high school on Friday.

Three students were injured, two of them seriously, in the attack in Fagersta, Sweden.

The alleged attacker is an 18-year-old, male student of the school who carried out the attack while classes were in session Friday. He was arrested and the police are investigating the case as murder and attempted murder. They said they have no reason to believe there were more attackers involved.

The Brinelskolan School principal told local news Saturday that the attacker was a student there.