The incident occurred a few hours after the Opotiki College ball - a bustling event on the social calendar with parties held throughout the town, residents say.
Rangimaria's grandfather Mike Davis told NZME the family still did not know what had happened to their "little girl".
"I don't know what to say," he said.
"My daughter's girl...I'm not sure what happened...We'll find out."
He said Rangimaria had only just moved away from the Opotiki area to Whakatane and was going to school at Edgecumbe College.
Flowers marked the roadside where she lost her life this morning.
"She told us she was going to stay with her mate and then wandered off, at night. There was a ball last night," Mr Davis said.
Police Inspector Willy Taylor said it was believed Rangimaria had been at a relative's house and left prior to the incident.
A post-mortem was being carried out today and a full police investigation would go ahead, he said.
"We do know that she was attempting to cross the road, we're unsure what condition she was in while she was doing that because we're still speaking to witnesses."
Goring St resident Lynn Roberts said the ball night was treated like a "party night" for the whole town.
A number of empty alcohol bottles were littered along the street near where the accident took place on Sunday morning, she said.
"It's a disaster," Ms Roberts said.
"It's really tragic. It was ball night last night, it's pretty much a town thing, it's a big deal. There were parties everywhere. People put a lot into it, they really make a big deal of it."
An outpouring of grief from the teen's family and friends has been seen on Facebook, with Levi Rose Lamaar saying the family was extremely upset by the news.
"The worst thing is hearing your dad cry over the phone and telling him everythings gonna be fine when holding back 1 million tears while he says 'thats not fair, shes only a little girl' [sic]."
Cousin Terri-lee White said she had been crying since she heard the news at 5am on Sunday.
"You know I love you my langilangi. forever and always my cousin to the end! I had your back since we were kids we done everything since we were born! Rest easily... I'm on my way down now to send you away," she posted.
Tutiyana Watson said: "Ugh, god took another angel from us, rest easy bby girl rangimaria white [sic]."
Opotiki mayor John Forbes said his thoughts were with the family.
"All I can say is my condolences go to the family. That's really, really sad. I'm just disappointed."
Tonight police communications manager Kim Perks said police were following up on information coming in from the public - by phone and social media - to see whether any of it was relevant.
She said there had been good public response to the incident and while some information was helpful, it was not necessarily directly involved with the incident itself.
"People that passed through the area just before, which is useful to us in terms of piecing together the kind of movements and timings.
"We're still working through all of that to see if we've got any specific witnesses to the actual incident itself."
People who were in Goring St between 3 and 4am on Sunday or had any possibly useful information should call Whakatane Police on 07 308 5255 or anonymously on Crimestoppers on 0800 555 111
