People of several nationalities were among the 11 killed at a school in Sweden’s worst mass shooting, police have said.

Anna Bergqvist, who is leading the police investigation, said people of “multiple nationalities, different genders and different ages” were among those killed by a lone gunman at Campus Risbergska, an adult education centre, in the city of Örebro on Tuesday.

Asked by reporters whether there was any evidence of racist motivation for the attack, Bergqvist said: “We are looking at all of those parts.”

The Syrian embassy in Stockholm said its citizens were among the dead. “With deep sorrow and grief, the embassy of the Syrian Arab Republic in the kingdom of Sweden expresses its strong condemnation of the criminal incident that took place in the Swedish city of Örebro, which resulted in … innocent victims,” the embassy wrote on its official Facebook page.

“It extends its sincere condolences to the families of the victims, including dear Syrian citizens, and to the friendly Swedish people, and we wish a speedy recovery to the injured.”

Among the victims was Salim Iskef, 28, who phoned his fiancee from the school and told her that he had been shot. “He called me and said, “I’ve been shot, they shot us.’ He said he loves me and that’s the last thing I heard,” Kareen Elia, 24, told SVT through tears. During the video call she could see somebody lying still beside him and blood on his hand.

The couple had planned to get married on 25 July. They had booked the venue and Elia, who moved to Sweden from Syria in 2015, had tried on her wedding dress.

She still does not know what happened to him and has not received an official death notice from police.

“I still want to believe that he might come home. We can’t sleep, we stand by the window waiting for him to come home. No one wants to believe that he is dead,” she told the broadcaster. “If he is not alive, we just want to see his body.”

A police spokesperson said they were unable to confirm any of the names of those who had died because the identification process was still ongoing.

Until now, police had revealed little about the victims or the gunman, other than that he was believed to have acted alone.

The suspected gunman, who was among the dead, was named in media reports as Rickard Andersson, 35, a former student of the school who lived locally. He is understood to have attended some maths classes at the school a few years ago and had been unemployed for a decade.

On Thursday, police again declined to confirm his identity until they had DNA confirmation. They previously said the suspect had no known connection to criminal gangs and that there was nothing to suggest he acted on ideological grounds.

Police said the suspect had a licence for four weapons, all of which have been seized by police and three of which were next to him at the scene when officers secured him.

Bergqvist said: “What we can say is that there is information that he may in some way be connected to the school, that he may have attended this school previously.”

Police said although “the picture is starting to clear” in the investigation, they were “not ready to give detailed answers. We want to be sure before we speak”. They said they had searched the suspect’s home, examined his phones and had been scouring film and sound clips submitted by witnesses.

They said officers were met by an “inferno” when they arrived at the school about five minutes after the alarm was raised at 12.33pm on Tuesday. Lars Wirén, Örebro’s police chief, said: “They [police] tell of what can be described as an inferno with dead people, injured people, screams and smoke.”

Shortly after they entered, they could see smoke rising and thought they were being shot at by an approaching gunman, he said. “They see a perpetrator armed with a rifle-like weapon.”

Magdalena Andersson, the leader of the main opposition Social Democrats and a former Swedish prime minister, said the school was known for having a diverse student body.

“We have to wait until the police investigation is finished to know anything about motive and also when they can say who this person was,” she said. “But what is well known is that this is a school with students from many parts of the world.”

Without the fast reaction of police, witnesses told her when she visited Örebro on Wednesday, the death toll could have been considerably higher.

The election in 2022 of Sweden’s Moderates-led coalition government, which depends on the support of the far-right Sweden Democrats, has led to increased anti-immigrant policies in Sweden, contributing to racist rhetoric and social polarisation.

Andersson said: “As a Social Democrat I have spent the last two years arguing that we need to keep together in our society. We have nothing to win from more division or more polarisation in our society. When we have done best in our country is when we have been able to stick together, work together and take care of each other.”

She called for immediate reconsideration of gun laws. “What we already know is that there are too many guns that are available in our society, so we have to do something about that.”

She also called for EU action to curb social media platforms that she said served up far too much violence to young people and children. “Not only in Sweden but all over the world, there is too much material on social media platforms that are romanticising violence. And the way the algorithm works, too many of our children, young people and others meet violence every day when they open their telephone.”

Since the shooting there have been growing calls – including from the education minister, Lotta Edholm, for changes to Sweden’s culture of open schools, which can make it easy for members of the public to walk into a school without being challenged.