A third person has been arrested on suspicion of involvement in the tram shooting in the city of Utrecht that left three people dead and five injured, Dutch police say.

Public prosecution office spokesman Ties Kortmann said three people were in custody – the alleged gunman Gokmen Tanis, 37, and two others who were also arrested on suspicion of involvement in the shooting on Monday morning.

Mr Kortmann said Tanis was being held on suspicion of manslaughter with a possible terrorist motive, but added that investigations were continuing into what drove him to allegedly open fire in a tram.

Netherlands shooting
(PA Graphics)

Prosecutors said the nature of the attack and a note found in a getaway car give them reasons to consider terrorism as a motive, but other possible motives are being investigated.

Dutch media said Tanis’s neighbours in Utrecht have speculated that the shooting may have been linked to a relationship, but prosecutors said investigations do not so far indicate the gunman knew any of the victims.

Earlier, justice minister Ferd Grapperhaus said Tanis “was known” to authorities and had a criminal record, but would not elaborate.

“If it had terror motives, that is being investigated. But it was very serious. The world shares our grief,” prime minister Mark Rutte said.

The attack came three days after 50 people were killed when an immigrant-hating white supremacist opened fire at two mosques in Christchurch, New Zealand, during Friday prayers.

Dutch authorities reduced the threat level in the city back to four out of five following the arrest of Tanis, which came after a manhunt involving heavily armed officers with dogs.

During the hunt, police released a photo of a bearded Tanis on a tram in a blue hooded top.

The arrest of Gokmen Tanis came after a manhunt involving heavily armed officers with dogs
The arrest of Gokmen Tanis came after a manhunt involving heavily armed officers with dogs (Police Utrecht/AP)

In the immediate aftermath of the attack, Dutch military police tightened security at airports and key buildings in the country, and Mr Rutte said: “If it is a terror attack, then we have only one answer: Our nation, democracy, must be stronger than fanaticism and violence.”

The shooting took place at a busy intersection in a residential neighbourhood.

Rescue workers remove a screen from the tram where the shooting took place
Rescue workers remove a screen from the tram where the shooting took place (Peter Dejong/AP)

Local media said Tanis had been charged several times over recent years with offences ranging from attempted manslaughter to petty crime in and around Utrecht. Two weeks ago he was in court on charges of raping a woman in 2017, news reports said.

The Netherlands’ anti-terror co-ordinator, Pieter-Jaap Aalbersberg, raised the threat alert to its highest level, five, around Utrecht, a city of nearly 350,000, until Tanis was captured.