The main suspect in a deadly shooting in a tram in the Dutch city of Utrecht has confessed to the attack and said he acted alone, prosecutors announced.

The shooting is being investigated as a possible extremist attack, but prosecutors would not say if the suspect, Gokmen Tanis, has said anything about his motive.

“The 37-year-old suspect this morning confessed the criminal acts he is charged with” at a hearing before an investigating judge, the public prosecutor’s office said in a statement.

NETHERLANDS Shooting
(PA Graphics)

Prosecutors did not elaborate on the confession and said the motive for Monday’s attack, which left three people dead and three more seriously wounded, remains under investigation.

Tanis, a Utrecht resident of Turkish descent, was arrested hours after the shooting and is being held on charges including multiple murder or manslaughter with terrorist intent.

Prosecutors have said Tanis, who has a long criminal record, did not know any of those who were shot on the tram, according to their investigations so far.

They say the nature of the shooting and a note found in a getaway car led to strong suspicions of an extremist motive.

A makeshift memorial site in Utrecht
A makeshift memorial site in Utrecht (Peter Dejong/AP)

On Thursday, the local prosecution office said investigations are also continuing into whether the suspect’s actions “flowed from personal problems combined with a radicalised ideology”.

The team investigating the shooting has asked a forensic psychiatry and psychology institute to carry out a personality test on Tanis.

At Friday’s closed hearing, an investigating judge extended Tanis’s detention by two weeks so investigations can continue. In a statement, the court said the judge ruled that “the suspicion is strong enough to detain the man for longer”.

A 40-year-old man who was detained a day after the shooting because Tanis was arrested at his home has been released without charge after no evidence was found that he helped in the shooting, prosecutors said.

Later on Friday, a silent march will be held from Utrecht’s main railway station to the junction where the shooting happened in a show of solidarity with the victims.

Prime minister Mark Rutte and the mayors of the Netherlands’ four biggest cities are to take part.