Carina Skagerlind, a press spokesperson for the Stockholm police, told Swedish Radio: "Our work continues with undiminished force. Like we've said before, this involves a number of investigative and surveillance measures."
Apart from the two individuals who are under arrest on suspicion of carrying out the attack, all others taken in for questioning over the weekend have been released, news agency TT reported on Monday.
Regarding the 39-year-old Uzbek man who is in police custody, Jan Evensson, a senior policeman involved in the operation, said on Swedish Television on Sunday that police were convinced they had the right man. If found guilty, the man will “spend the rest of his life in jail," said Evensson.
The 39-year-old had gone underground in Sweden after his asylum application was rejected last year.
Four people were killed in Friday’s attack: two Swedes - including an 11-year-old girl - a British man and a Belgian woman. As many as 15 others were injured in the attack, nine of whom remain in hospital and two are in intensive care.
On Monday morning, Drottninggatan, the scene of the attack, was once again filled with Stockholmers commuting to work, with most stopping only a few seconds to stop and survey the flowers and notes laid in remembrance.
"I just want to cry," Fadi Mdalal, who is from Syria, told TT. "I am so sad for Sweden. Too many people have died here – for nothing."
Stockholm city council has opened a crisis support centre in the central Stockholm district of Kungsholmen where counselling will be offered for those disturbed by the attack.
A minute's silence will be observed at 12 noon across Sweden. It will coincide with a memorial service to be held outside Stockholm City Hall.