"There won't be a parent or person in the district that isn't feeling for those families," he said. "It's hard to find the words.
"We're a small community and losses like this one are ... are hard to take any time."
Ms Moyes was riding on the passenger side of the car when the crash occurred on State Highway 2 on the southern approach to the Opaki overbridge north of Masterton shortly after 3pm on Thursday.
She sustained head and spinal injuries.
Ms Moyes was a student at Ucol Wairarapa, as was the 19-year-old driver of the car.
The driver was taken by ambulance to Wairarapa Hospital with minor injuries but had since been discharged, as previously reported by the Times-Age.
The stretch of highway where the crash occurred had been blocked to traffic for about four hours on Thursday while a serious crash unit team examined the crash scene.
Mr Mark said a loss of a child is extremely hard for any parent, as he had personally experienced.
"We'll get through as a community," the mayor said.
"It's not just Carterton, it's the whole lot of Wairarapa."
It was understood Ms Moyes was a former Kuranui and Chanel College student.
In the other incident, 15-year-old Ms Diedrichs was killed in a ute collision with a passenger train on Wiltons Rd.