They were William Brown, 46, Shylin Huirana-Osbourne, 26, and Sione Nusipepa, 23.
Police said all three were inside the SUV when there was an accident with a train on the Peachgrove Rd rail crossing in Hamilton at 4.30am on Wednesday.
Two others inside the car were injured and remain in Waikato Hospital.
“Police extend our condolences to their whanau and loved ones.”
Police thanked all members of the public who responded and assisted with the incident.
“The full circumstances are still under investigation, and as part of our inquiries, police would like to speak with all members of the public who assisted.
“In particular, police would like to speak to the occupants of a vehicle that was stopped at the crossing barrier arm when police arrived on the scene,” police said.
“I would like to acknowledge the actions by members of the public and emergency services who responded and managed what was a difficult scene,” she said.
“We will ensure there is support in place for those involved, their families and our staff who attended.
National rail safety charity TrackSafe said the accident was devastating and a reminder to everyone of the risks at railway level crossings.
Foundation manager Megan Drayton said while collisions at railway crossings were relatively rare, the consequences were often catastrophic.
“This collision is an example of that, and we extend our deepest sympathies to all affected, the friends and whānau of the victims, and the rail staff and emergency services involved,” she said.