Updated 6.45pm 

Around 10 people were killed in a shooting at an education centre in central Sweden on Tuesday, including the suspected assailant, police officials said.

The shooting was the deadliest school attack in the country's history.

"Around 10 people have been killed today," Orebro police chief Roberto Eid Forest told reporters, adding that police could "not be more specific about the number due to the large number of wounded".

He provided no details about the number of wounded.

"This is a terrible event. This is exceptional, a nightmare," Forest said.

Police did not disclose any information about the identity or ages of the dead, nor whether they were students or teachers at the Campus Risbergska secondary school for young adults.

Several media reported the suspected gunman turned his gun on himself but police would not confirm those reports.

"The suspected assailant is not known to police. He has no connection to any gang," Forest said, referring to the surge in deadly shootings and bombings linked to gang violence that have plagued Sweden in recent years.

"We don't expect any other attacks," Forest said.

School attacks are relatively rare in Sweden, which has in recent years grown more accustomed to shootings and bombings linked to gang violence that kill dozens of people each year.

A police officer cordons off an area near the Risbergska School in Orebro, Sweden. Photo: AFP

"The extent of the injuries is unclear. The operation is ongoing," police said in a statement.

Police initially said that four people had been shot, but updated the tally minutes later to five and later to "around 10". 

A teacher at the school said he was in the school when he heard gunfire.

"I heard shots fired, so I've barricaded myself and am waiting for news. We have an alarm on our security app and I'm communicating with my colleagues," Petter Kraftling told the online union newspaper Vi Larare.

The crime was being investigated as "attempted murder, arson and an aggravated weapons offence", police said.

Members of the public were urged to stay away from the area, or stay inside their homes.

In an update just after 2pm, police stressed that "the danger is not over. The public MUST stay away".

Newspapers Expressen and Aftonbladet reported that police had been fired on at the scene, but police said in a statement no officers had been wounded during the operation.

Schools in lockdown

Students in nearby schools and the school in question had been locked in "for safety reasons", police said.  

Speaking to public broadcaster SVT, Justice Minister Gunnar Strommer said the reports were "very serious".

"The government is in close contact with the police and is closely following developments," Strommer told SVT.

According to several Swedish media, witnesses reported hearing what they believed to be automatic gunfire.

Aftonbladet wrote that it had received reports that the local hospital had emptied its emergency room and intensive care unit in anticipation of the arrival of the wounded people.

Though school attacks are rare, several serious incidents have taken place at schools in recent years.

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

Two months earlier, a 16-year-old was arrested after wounding another student and a teacher with a knife at a school in the small town of Kristianstad.

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 later killed by police