Senior Sergeant Richie Thompson told the Herald that members of Matthes' family were out looking for the boy after he was late arriving home and saw the emergency services in attendance at the Ranui train station.
They found out that he had been killed at the scene.
The Herald understands Matthes, a talented up-and-coming rugby player, was the grandson of Denis Wilmott Hansen QSM.
Hansen, a well-respected West Auckland kaumatua, suffered a heart attack in his car in 2013.
He was kaumatua for the Waitemata and Auckland district health boards for many years.
In 2010 Hansen received a Queen's Service Medal for more than 30 years service to Maori and the community.
Police are investigating the circumstances of Matthes' death and said it would be referred to the Coroner.
His family and friends paid tribute to Matthes on social media.
"You left us to early brother, may God give him external rest and his family the strength to bear the great pain," wrote one friend on Facebook.
"Now who am I gonna talk to about our favorite soccer team?
"You have left us but you will never be forgotten."
Matthes was a promising rugby player and was a member of the Waitemata Rugby Football Club.
The Herald has learned that a minute silence will be held before the club's main game on Saturday and the team will wear black arm bands in memory of Matthes.
Last year Matthes was named in an under-16 representative team.
Matthes' tragic death fell on the New Zealand rail industry marks Rail R U OK? Day which focuses on creating a more supportive environment for rail workers exposed to trauma on the job
The initiative was founded by TrackSAFE Foundation, and chairman Bob Herbert said depression, anxiety and mental trauma are "very real issues impacting rail staff and first responders, and regular meaningful conversations can really help".
-Additional reporting Ben Hill
