Hundreds of floral tributes have been laid in Stockholm just 24 hours after a lorry attack killed four people in the Swedish capital.
The Scandinavian country's prime minister Stefan Löfven was among those to lay flowers in memory of the victims.
In the wake of the attack he urged Swedes to "get through this", and strolled through the streets to chat with people.
A "suspect device" was found in the driver's seat of the lorry used in the Stockholm attack, police have said.
At a press conference, detectives also revealed the 39-year-old suspect from Uzbekistan was known to security services but that the intelligence was "marginal".
The man is not thought to have spoken to detectives since he was arrested yesterday.
ITV News reporter Sally Lockwood said Swedish police are drawing "clear similarities" with the Westminster attack on 22 March.
The Swedish prosecutor has confirmed that the man suspected of carrying out Friday's lorry attack in Stockholm is a 39-year-old man from Uzbekistan.
Security services had intelligence on him but he was regarded as a marginal character, police said.
Swedish Police: Supect is a 39yo man from Uzbekistan. Security services had intelligence on him but he was regarded as a marginal character
He was arrested in the north of the city on Friday after a high-speed police chase.
- Video report by ITV News Reporter Ivor Bennett
Dramatic footage of a high-speed police chase has emerged of detectives closing in on the man they believe was responsible for carrying out Friday's deadly lorry attack in Stockholm.
The chase ended in countryside north of the city, where the man was detained.
Officers said the suspect matches the description of a man they were hunting after he was spotted near the attack in the Swedish capital.
Prime Minister Theresa May has spoken with her Swedish counterpart and offered to work together against extremist attacks.
Downing Street said she had expressed condolences on behalf of the British people in a telephone call to Swedish Prime Minister Stefan Lofven.
The statement said the two leaders agreed on the importance of working together to tackle such threats.
Britain was hit by a similar attack last month when a man drove a car into pedestrians before stabbing a policeman to death outside the Houses of Parliament.
Five of the 15 people who were injured in the Stockholm lorry attack have been released from hospital.
Sweden's health service said four of the 10 remaining were seriously injured and two are in intensive care.
It added that the one child still in Karolinska Hospital was not seriously injured.
Four people were killed when the driver of a hijacked truck ploughed into a group of pedestrians in central Stockholm on Friday.
Swedish police said they have arrested a man who is "likely" to be the culprit.
A man arrested following the deadly lorry attack in Stockholm is "likely" to be the driver of the hijacked truck which ploughed into pedestrians, Swedish Police said.
The man was detained in a northern Stockholm suburb on Friday and later arrested on suspicion of "terrorist crimes through murder".
Four people were killed after the beer lorry crashed into a department store in the Swedish capital on Friday afternoon.
"Yes, it is correct, it is likely him," police spokesman Lars Bystrom said on Saturday.
"The person in question has been arrested as the culprit, in this case the driver," he added.
The prosecutor, Hans Ihrman, said that the unidentified suspect should face a pre-trial custody hearing before midday on Tuesday or be released.
Officials also confirmed that only one person has been arrested in the case, contrary to media reports that two had been detained.
Beauty products remain on display yards from where a department store shop window was smashed in during Friday's deadly lorry attack in Stockholm city centre.
Swedish police have cordoned off the attack site and towed the vehicle away as an investigation gets underway.
Four people were killed after the hijacked lorry was driven along the pedestrianised street, Drottninggatan, in the busy shopping district before crashing into the Ahlens department store just before 3pm local time.
The lorry used in the suspected terror attack in Stockholm has been towed away from the central shopping street.
Swedish police said cordons around the crime scene would remain in place until the on-site investigation has been completed.
The first man arrested in connection with Stockholm's lorry attack is being held "on suspicion of terrorist crimes through murder", the office of the Swedish prosecutor has said.
It is the strongest degree of suspicion in Sweden's legal system, which can apply several different levels to hold a person.
Police confirmed he was now under "prolonged arrest".