At least three were killed after a truck ploughed into pedestrians on a busy shopping street in the centre of Stockholm on 7 April. Swedish police launched a manhunt for the lorry driver who fled the scene.
Here's what happened:
- At least three people were killed and eight injured in the attack, according to Swedish police.
- Sweden's Prime Minister Stefan Lofven said that everything indicated that the incident was "a terror attack."
- The incident happened outside the Ahlens mall in Drottninggatan, a pedestrianised street in the centre of Stockholm. When the lorry crashed into the shopping mall, a fire broke out and fire crews rushed to the scene.
- The central train station was closed and police cautioned people to stay away from the area. The station was surrounded by heavily armed officers.
- The Swedish parliament was on lockdown following the attack.
- Police launched a manhunt for the suspect and released an image of a man wearing a green jacket, white shoes and a grey jumper who they wanted to speak to in connection with the attack.
- The truck crashed into the crowd yards from where a suicide bombing happened in 2010.
Paris' mayor says the lights of the Eiffel Tower will be turned off at midnight in homage to the victims of the attack.
There are conflicting reports on the number killed in the attack, with police saying three were killed, while earlier local media reports said as many as five may have died.
Russian President Vladimir Putin has sent a telegram of condolence to Sweden's king. It is only four days since a suicide bomb on St Petersburg's metro killed 13.
"In our country, people know, and not by hearsay, about the atrocities of international terrorism," he wrote. "At this difficult time, Russians mourn together with the people of Sweden."
Following the attack, police at Oslo airport and in the largest Norwegian cities will be armed until further notice, police said in a statement. Police officers in Norway, which borders Sweden, do not normally carry weapons.
Police are holding a press conference in Stockholm.
"A truck drove into Ahlens on Drottninggatan. We have truck and are in contact with the person who normally drives the truck," says Sweden's national police chief Dan Eliasson.
He said that the person driving the truck at the time of the incident is not in custody, and did not know if the attack is an isolated incident.
They have released the above image of a man seen in the area they would like to trace.
According to local journalists, police are hunting a suspect wearing a green jacket, white shoes and a grey hoodie.
Sweden's King Carl XVI Gustaf has released a statement about the incident.
"I and the entire royal family have sadly been informed about this afternoon's attack in Stockholm. The background to and extent of the incident is not yet know. We are following developments but our thoughts already go to those affected and their families," the statement reads.
Sources have told Sky News that a manhunt is underway for the Stockholm attack suspect, who is thought to have run towards a subway station.
Swedish Prime Minister Stefan Lofven said that a person was arrested after the attack, however Stockholm police said no-one has been arrested.
Pictures showed armed police entering Stockholm's Central Station earlier, which was evacuated.
The truck crashed into the crowd yards from a 2010 suicide bombing during the Christmas period that killed the perpatrator and injured two people, reports the Local.
Swedish security service Säpo say that a "large number of people are injured", and that they are now assisting the police in an investigation. "Intensive intelligence work is being conducted in order to identify the person or persons behind the attack," they add.
Police said there were no shots fired in the Fridhemsplan district in the north of the city, rowing back on an earlier report.
Stockholm metro and commuter rail service has been closed down in the wake of the attack, police said.
Video footage of Swedish PM Stefan Lofven speaking in the wake of the attack.
Further footage obtained by Aftonbladet of the aftermath of the attack on a busy shoping avenue shows victims lying on the street, with shouts heard.
European Council President Donald Tusk has expressed his sympathies for the victims of the attack.
Dramatic pictures have emerged of the aftermath of the incident, when the truck seemed to burst into flames after hitting the building.
A hotline has been set up for those concerned that they know someone caught up in the attack, who are asked to call 11414 and select option 9.
Israeli President Reuven Rivlin has condemned the attack.
Swedish tabloid Expressen is reporting that heavily armed police have arrived in Central Station.
Stockholm Police said that while people have been injured in the incident they have no details about their situation or about the number of those injured.
Swedish police have ordered the evacuation of the Central Train Station following the terror incident, according to TT news agency.
Dagens Nyheter has an alleged picture of the arrest in central Stockholm that took place in the wake of the incident.
The US Embassy in Stockholm has urged its citizens to avoid the area of the attack.
"The U.S. Embassy in Stockholm is aware of reports of a security incident at Drottninggatan and Mäster Samuelsgatan near Sergels Torg in Stockholm City Center. U.S. citizens should avoid this area at this time, heed guidance from local authorities, and maintain security awareness," it said in a statement.
Footage of the aftermath of the incident purports to show black smoke billowing from the crashed lorry, and fire crews at the scene extinguishing the blaze.