Danish police say a gunman who killed three people when he opened fire on Sunday in Copenhagen’s Field’s Shopping Centre acted alone.

Authorities say he selected his victims at random all but ruled out Monday that attack was an “act of terrorism”.

The three killed were a 17-year-old boy and a 17-year-old girl, both Danes, and a 47-year-old Russian man.

Four more people were hospitalized with gunshot wounds in critical but stable condition.

A total of 30 people were hurt. Most were injured in the panicked crowd after the shots rang out at the mall.

Police have not identified a motive for Sunday’s attack at one of Scandinavia’s biggest shopping centers. The 22-year-old Danish man carrying a rifle and knife was quickly arrested. Police say the suspect also had access to another gun. The firearms were obtained illegally.

The suspect was known to mental health services but gave no further details on either.

“It was the worst possible nightmare,” Danish Prime Minister Mette Frederiksen said Monday, calling the attack, “unusually brutal.”

The last shooting on this scale was in February 2015, when a 22-year-old man was killed in a shootout with police after an attack in the capital that left two people dead and five police officers wounded.

The suspect arrived for a hearing in a packed courtroom, where he is expected to be arraigned on three preliminary charges of murder and four of attempted murder, according to Danish media.

Sunday’s attack came about a week after a shooting in Norway, where a man opened fire during a LGBTQ festival. He killed two and wounded more than 20.