Utrecht, Netherlands -- Dutch prosecutors said Tuesday that they were taking seriously the possibility that a man suspected of killing three people and seriously wounding three more in a shooting on a tram in Utrecht had a terrorist motive. In a statement, prosecutors said the nature of the attack and a note found in a getaway car give them reason to consider terrorism as a motive. They said other possible motives were also being investigated, however.

The prosecutors also said the investigation so far did not indicate that the main suspect, a 37-year-old man of Turkish descent who was arrested hours after Monday's attack, knew any of the victims.

Prosecutors said a weapon was recovered when he was arrested.

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The statement said three people were seriously wounded in the shooting and four more suffered minor injuries.

Dutch Justice Minister Ferd Grapperhaus said on Monday that the alleged shooter, identified as Turkish-born Gokmen Tanis, 37, "was known" to justice authorities and had a criminal record, but would not elaborate.

A photo sent by the Utrecht Police in the Netherlands on March 18, 2019, shows a man identified as Turkish national Gokmen Tanis, whom the police were seeking in connection with a deadly shooting attack on a tram in Utrecht. Handout

In Turkey, President Recep Tayyip Erdogan said on television that the country's intelligence agency was investigating whether the attack was terrorism or personal.

3 people in custody

Dutch police said Tuesday that they had arrested a third person on suspicion of involvement in the tram shooting in Utrecht.

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

The role that the two additional suspects might have played in the crime remained unclear.