The person is in a serious condition.
Motorists should avoid the area and use an alternative route, police said.
KiwiRail operations executive general manager Paul Ashton said none of the eight passengers or five crew onboard the train were injured.
“The train remains at the scene pending inspections of the locomotive and track. We expect it will then continue on to Masterton.
“The level crossing, which has flashing lights and warning bells, suffered extensive damage.”
The cause of the crash will be investigated, Ashton said.
Metlink group manager Samantha Gain said passengers were able to safely get off the train and were moved to Masterton, where a bus replacement service was arranged.
“The accident has caused damage to the level crossing equipment, which has resulted in a temporary 10km/h speed restriction through level crossings at Norfolk Road and Norman Ave being imposed until the equipment can be repaired.”
Several Wairarapa Line services have been replaced by buses, with further disruption possible, Gain said.
“Train services will resume when it is safe to do so, however Wairarapa rail passengers, including travelling Women’s World Cup fans, are encouraged to plan ahead and check the Metlink website and app for updates.”