Man, 21, in mask and helmet launch attack on school in Sweden

The 21-year-old man, who launched a sword attack on a school in Sweden and stabbed two teachers and two pupils, stopped to pose for pictures with students before continuing his horrific spree.

Wearing a mask and holding a sword already covered in blood, the attacker, stands next to two young students at the school, seconds before stabbing a teacher, who died at the scene.

Another teacher was rushed to hospital alongside the injured students, two boys aged 11 and 15. The 11-year-old later died from his wounds.

The MailOnline understands the suspected killer to be Anton Lundin-Petterson, from Trollhättan, north of Gothenburg.

Killer: The 21-year-old posed for this picture moments before he stabbed a second teacher in the attack in Trollhattan, Sweden

The MailOnline understands the suspected killer to be Anton Lundin-Petterson, pictured, from Trollhättan, north of Gothenburg

Forensic officers investigate at a primary and middle school in Trollhattan tonight after the incident

The anonymous girl who took the photograph told Swedish newspaper Aftonbladet that they thought it was a Halloween prank when they saw the masked man.

As Lundin-Pettersson allegedly moved across the school during his attack, the young student had no idea that the blood on the large sword he was holding was real.

She told the newspaper that she had left her classroom to fetch a pen when she spotted two friends standing with a man wearing a mask and holding a blood-covered knife.

Thinking that the attacker had dressed up as a holiday joke, her friends wanted a picture with him, so she obliged.

Seconds after the picture was taken, their teacher came out of the classroom and told the killer to leave as he was scaring the children.

'He just nodded, then he plunged the large knife into the teacher's right side. The last thing I heard him say was "call an ambulance".'

Flowers and candles have being left the scene of a primary and middle school in Trollhattan

A forensic officer investigates the scene where two teachers and two pupils were stabbed at a school in Sweden

Sword attack: One teacher and one student has died in the wake of the attack, one young boy and a second teacher is still in critical condition in hospital

Kronan is located in an area of Trollhattan with a diverse population and many of the pupils are first or second generation immigrants.

In the weeks before the attack, Lundin-Pettersson, who was described by witnesses as wearing a 'Darth Vader mask and helmet', had expressed sympathies with extreme right-wing organisations online.

An investigation by magazine Expo into Lundin-Petterson's social media activities found that he had 'liked' several YouTube videos glorifying Nazi Germany.

He had also showed support for anti-immigration party Sweden Democrats, and other right-wing politicians on Facebook.

He attended technology school Lichron Teknikgymnasium Trollhättan.

Racist attack: The 21-year-old had 'expressed right-wing and Nazi sympathies' online in the weeks before the attack at the school, which is located in an area of the city with a large immigrant population

Chaos: Family members fight police to try to get access to the school as hundreds of students remained inside in the first hours after the attack

Police arrived at the scene shortly after 10am and were forced to shoot the 21-year-old attacker after he turned on police.

The assailant used 'a number of knife-like weapons' to attack students and teachers in the school cafeteria and in classrooms.

'One of my friends opened the door and there's a man dressed in black with a Star Wars mask and a large black sword,' a student witness told Sveriges Television.

Parents and children walk away from the school as crowds gather to learn more about the attack

Two people light candles in memory of the teacher and 11-year-old boy who were killed in the attack

Swedish emergency services at the scene after a masked man attacked people with a sword at the Kronan school in Trollhattan in western Sweden

The victims and the masked attacker were all rushed to the Norra Alvsborgs Lanssjukhus hospital in Trollhättan, an industrial town of around 50,000 inhabitants.

Speaking at a press conference on Thursday afternoon, police addressed speculation that the attack had racial motives.

'It's in the picture[potential racist attack], but it is nothing I wish to comment on at the moment,' Thord Haraldsson, who is leading the investigation said.

The wounded teacher had been stabbed in the abdomen while the boys were stabbed in the abdomen, liver and chest.

The attacker, who was also admitted to the Norra Alvsborgs Lanssjukhus, had gun wounds to the lower part of his chest, and later died from his wounds.

Kronan has around 400 students from pre-school, aged six, up to year 9, aged 15-16, but the murdered is not a former pupil.

The victims and the masked attacker were all rushed to the Norra Alvsborgs Lanssjukhus hospital in Trollhättan, an industrial town of around 50,000 inhabitants

Panic: Families and relatives wait outside the school as students were kept inside by police for safety reasons

Police responded to an emergency call saying a masked man equipped with a sword was on the premises and that a person had been attacked at or near the school cafeteria, police said

Speaking at a press conference on Thursday afternoon, Tomas Fuxborg of Västra Götaland Police called the attack 'one of the worst events in Swedish history'.

Swedish Prime Minister Stefan Lofven, who was heading to Trollhattan, described Thursday as a 'black day.'

'My thoughts go out to the victims and their families, the students and staff, and the whole community that has been affected,' Lofven said.

'No words can describe what they are going through right now.'

King Carl XVI Gustaf of Sweden has also made a a statement in the wake of the attack:

'Sweden is in shock. It is with great dismay and sorrow that my family and I have received the news about the events in Trollhättan.