The death toll from this month's truck attack in Sweden's capital rose on Friday after a woman in her 60s passed away, police said.

"A woman of around 60, who was being treated in an hospital in southern Sweden for injuries she received in connection with the terror attack on Drottninggatan, died on the morning of April 28," Swedish police said in a statement. They did not publicly identify the woman.

The other four victims were identified earlier as a British man who worked for the music-streaming service Spotify, a Belgian woman, a Swedish woman in her 60s and an 11-year-old Swedish girl.

A further 14 people were injured in the April 7 attack when a hijacked truck plowed through a busy pedestrian shopping area in Stockholm.

A 39-year-old Uzbek national, Rakhmat Akilov, confessed to driving the stolen truck and pleaded guilty to a terrorist crime. He is being held in custody, but police have been looking for possible accomplices.

Police arrested a second suspect on Monday, who was then released on Wednesday. The person is no longer a suspect in the case, prosecutors said in a statement.

Akilov's Swedish residency application was rejected in June last year. After receiving a deportation order, he went underground, but police said there was nothing to indicate that he might plan an attack.

Swedish authorities have not yet released a motive for the attack and no extremist group has claimed responsibility.

The Stockholm attack was the fourth time in the past 12 months that a vehicle has been used to target a crowd of civilians in Europe. It follows the deadly attacks in London, Berlin and Nice.

rs/rt (AP, dpa, Reuters)