Authorities in the Netherlands said Tuesday they were investigating terror as a possible motive behind a shooting on a tram that left three people dead and five others wounded in the city of Utrecht.
Dutch police and prosecutors said in a joint statement "a terrorist motive is seriously being taken into account ... based on a letter found in the getaway car among other things and the nature of the facts."
Prime Minister Mark Rutte said earlier authorities "cannot exclude" other motives, including a family altercation. The Turkish news agency Anadolu reported that relatives of Tanis in Turkey said the shooting could have been part of a family dispute.
Police arrested a suspect identified as 37-year-old Turkish-born Gokmen Tanis hours after a manhunt that lasted several hours Monday.
By Tuesday they said no direct link had been found between the suspect and the shooting victims, but prosecutors said Tuesday he is suspected of the three fatal shootings with possible terrorist intent.
In addition to the main suspect, two other people have been detained, but authorities have not detailed their possible roles in the attack.
A Dutch regional prosecutor said the suspect had previously been arrested in the Netherlands. Tanis was convicted of illegal weapons possession in 2014 and for burglary and shop lifting earlier this month. He was released from jail on March 1 after being detained on suspicion of rape, the Utrecht District Court said.
Dutch law requires Tanis to appear at a court hearing on the shootings by Thursday but he does not have to be charged on that day.
Security has been increased at Dutch airports, as well as mosques. Schools in Utrecht have been closed, and residents were advised to stay home.
Political parties suspended campaigning for provincial elections scheduled for Wednesday that will also determine the makeup of the Dutch senate.
Utrecht is the fourth-largest city in the Netherlands, known for its canals and large student population. Gun violence in the city is rare, as it is across the Netherlands.