March 19 (UPI) -- Dutch police said Tuesday they have detained three suspects in connection with a tram shooting that killed three people in Netherlands.
Police said they found a letter in a getaway car used by Turkish suspect Gokman Tanis that reinforces authorities' belief Monday's shooting in Utrecht was a terrorist attack.
Other motives are being explored, Utrecht police and public prosecutor said in a joint statement. The contents of Tanis' letter wasn't specified.
Police tracked down Tanis, 37, by analyzing surveillance footage in the area and the getaway vehicle. He was armed when confronted by police, officials said. No additional details were released on the other two suspects.
Among the dead is a 19-year-old woman, a 28-year-old man and a 49-year-old man. Investigators said it doesn't appear the gunman knew any of the victims. Utrecht is about 25 miles southeast of Amsterdam.
Five people were hurt in the attack, three seriously.
Dutch King Willem-Alexander and Queen Maxima said in a statement "violence is unacceptable."
"It hurts us very much that three people have died today and others got hurt," they said. "Let's stand together for a society where people feel safe, and freedom and tolerance are leading."