The small Swedish town of Vetlanda was in shock on Thursday, reeling from a stabbing attack that left seven injured, while police said it was too early to determine the motives of the suspected 22-year old Afghan assailant.

Authorities said Thursday the case was being treated as attempted murder, while police said they were investigating "potential terror motives."

"The motive is an important aspect of the investigation as it could affect the potential charge," regional police chief Malena Grann told a press conference, adding that the attacker seemed to have acted alone.

Police initially treated the incident as "attempted murder" but later changed it in a statement to include a "suspected terrorist crime"
Police initially treated the incident as "attempted murder" but later changed it in a statement to include a "suspected terrorist crime" TT NEWS AGENCY / Mikael FRITZON

While stressing that the investigation is in its early stages, Grann said police had already questioned witnesses, collected evidence and searched the man's residence.

Police had informed the arrested man, identified only as a 22-year-old with Afghan citizenship, that he was a suspect but had yet to question about the actual act.

All the injured were men, born between 1945 and 1985.

A heart-shaped bouquet of roses on Vetlanda's main street a day after the stabbing attack
A heart-shaped bouquet of roses on Vetlanda's main street a day after the stabbing attack AFP / Jonathan NACKSTRAND

"There is currently nothing that indicates any type of relation between the suspect and the plaintiffs," local police chief Jonas Lindell told reporters.

Police officers patrol Vetlanda a day after the stabbing attack
Police officers patrol Vetlanda a day after the stabbing attack AFP / Jonathan NACKSTRAND

The suspect was taken to hospital after being shot in the leg by police following the attack in the town of 13,000 people in southern Sweden.

"Right now we are a municipality in shock and given what we are hearing from elsewhere the whole country is in shock," Vetlanda Mayor Henrik Tvarno told a press conference.

"There are so many questions that we are looking for answers to. What has happened, what is behind this? It is a nightmare," Tvarno added.

Prosecutors say the case is being investigated as attempted murder, but police also spoke of details indicating "potential terror motives"
Prosecutors say the case is being investigated as attempted murder, but police also spoke of details indicating "potential terror motives" AFP / Jonathan NACKSTRAND

On Thursday, several police officers patrolled the area where the bloody attack occurred the day before.

A heart-shaped bouquet of red roses and candles was placed near the scene of one of the stabbings.

"It's a small town and we've never had something like this happen before and I think it's quite shocking," 54-year-old Vetlanda resident Ulrika Lovfor told AFP.

Three of those attacked were said to have suffered life-threatening injuries, but were in stable condition, while two others were in serious condition, according to the local health authority in Jonkoping where they were being treated in hospital.

A heart-shaped bouquet of roses was placed on Vetlanda's main street
A heart-shaped bouquet of roses was placed on Vetlanda's main street AFP / Jonathan NACKSTRAND

Public prosecutor Adam Rullman also told AFP on Thursday that in the event of it being designated a terrorist crime it would be handled by a special unit within the Prosecution Authority.

"They have not deemed it necessary for them to take over the investigation at this stage," Rullman added.

The prosecution authority later said in a statement that they had requested the district court to remand the suspect in custody, with a hearing expected on Friday.

According to media reports, the suspect arrived in Sweden in 2018 and was awaiting a decision on a residence permit.

Several thousand young Afghans have travelled to Sweden to seek asylum in recent years, with many arriving via Iran.

Initial reports said eight people hade been injured but a police statement early Thursday revised the number to seven.

The suspect was a resident of the area and previously known to police, but in the past had only been accused of "petty crimes", including small-scale cannabis use, according to local media reports.

Speaking at a press conference on Thursday, Prime Minister Stefan Lofven called it an "attack on innocent people" but he too noted the investigation remained an attempted murder probe.

"A lot is still unknown, but one thing is certain and that is that every attack against innocents will be met by the joint strength of all of Sweden," Lofven said.

Swedish intelligence services say the possibility of an Islamist extremist attack was considered high, with the Scandinavian country having been targeted twice in recent years.

In December 2010, a man carried out a suicide bomb attack in the centre of Stockholm. He died after only slightly injuring passers-by.

In April 2017, a radicalised Uzbek asylum seeker ran over pedestrians in Stockholm with a stolen truck, killing five people. He was sentenced to life in prison.

The country has also seen extremist violence linked to the far-right.

In 2015, a racially motivated attack at a school left three dead.