Regional police chief Lars Wiren said officers arriving at the scene, where the gunman had killed 10 people before apparently killing himself, had described a scene resembling "an inferno".

Wiren said officers sent to the adult education centre in Orebro, west of Stockholm, were faced with "dead people, injured people, screams and smoke".

Releasing a timeline of the attack, police described how the first officers arrived at Campus Risbergska five minutes after police received several reports about a shooting at 12:33 pm (1133 GMT).

Shortly afterwards, officers reported smoke spreading through the building. They saw what they perceived to be "the shooter armed with a rifle-like weapon", said the police statement.

Within around 10 minutes of the first alert, a specialist first-response team had arrived and entered the building.

Wiren told reporters that officers got the impression that "the shooting started being directed at police when they entered the school instead of students and staff".

After a "time-consuming search" of the partially smoke-filled premised which lasted about an hour, they found the suspected shooter "dead with several weapons next to him".

Officers also found 10 empty magazines at the site and "a large amount of unused ammunition" next to the suspected gunman, who had turned the gun on himself and was dead when police reached him.

In all, around 130 officers attended the incident.

- Motive investigated -

Anna Bergqvist, who is heading the investigation, said they were still working to pin down a motive for Tuesday's massacre, which has sent shockwaves across the Nordic country.

"What is the motive? ... We don't have an answer yet," she told reporters.

Broadcaster TV4 published a video filmed by a student hiding in a bathroom in which shots can be heard outside and a person can be heard shouting: "You will leave Europe!"

Bergqvist told AFP there were "multiple nationalities, different genders and different ages" among those killed.

Some of the victims have yet to be identified, said police.

The Syrian embassy, expressed its "condolences and sympathies to the families of the victims, among them Syrians", in a Facebook post late Wednesday.

It told AFP it was waiting for police to confirm the total number but said they had "contacted the families of two Syrian victims".

Bosnia's foreign ministry said Thursday a Bosnian woman had been killed, citing family members of the victim who had contacted their embassy.

- Media names 'suspect' -

Swedish press have identified the suspect as 35-year-old Rickard Andersson, but there has been no official confirmation of his identity.

Swedish media reports painted a picture of the suspect as a local man who had been living as a recluse and was suffering from psychological problems.

Aftonbladet newspaper said he had hid his weapons in a guitar case and changed into military style garb in a school bathroom, before opening fire.

Bergqvist told reporters police believed they knew the identity of the assailant but would "not confirm such information" until they had verified the identity via DNA.

Police also said they believed he had acted alone and that several long-barrelled weapons had been recovered.

"He has a licence for four weapons, all of the four weapons have been seized," said Bergqvist. "Three of those weapons were next to him."

The man had previously been enrolled at the school but had not attended classes there since 2021, Aftonbladet reported.

Health authorities said Wednesday that six people were being treated at Orebro's university hospital.

Three women and two men had undergone surgery for gunshot wounds and were in a "stable but serious" condition, while a sixth woman was treated for minor injuries.

- 'Incomprehensible' -

Near the crime scene, people had put down notes among the tulips, roses, chrysanthemums and candles laid in memory of the students.

School attacks are rare in Sweden but shootings and bombings linked to gang violence have killed dozens of people each year.

In March 2022, an 18-year-old student stabbed two teachers to death at a secondary school in the southern city of Malmo.

In October 2015, three people were killed in a racially motivated attack at a school in the western town of Trollhattan by a sword-wielding assailant who was killed by police.