He said there was a strong smell of alcohol and several alcohol containers in the car, however the cause of the accident has not been determined.
Jackson's uncle Arthur Keane said the boys were not "drunken louts" but good hard-working boys who loved life.
He said Jackson's parents were too distraught to talk to the Herald on Sunday.
"There is going to be a huge hole in three families and we hope it's not going to be four," Keane said.
Keane said the teenagers met at Rosehill High School in Papakura.
"They did everything together, hunting, fishing ... they were not the kind to sit in front of TV screens and play video games, they just loved the outdoors."
Members of the Bombay Rugby Club gathered at Jackson's family home yesterday where they shared stories about their teammates.
Jackson and Jones played for the club's under-21 team while the other two boys often cheered them on from the sidelines.
Club captain Mark Rose said the under-21 game against Manurewa was cancelled yesterday and the premier team had a minute of silence before kick-off.
"The whole team are really tight and hopefully this will just make the team stronger, but there is a fair bit of grieving going on," Rose said.
He said Jones was given the nickname Dougie because of his black shaggy hair and talented rugby skills resembled former All Black Dougie Howlett.
Rose gave Jones' rugby jersey to his parents yesterday so he could be sent off in a jersey that he'd worn proudly.
The families were waiting for the coroner to release the boys' bodies before making any funeral arrangements.
"Everyone is absolutely devastated and trying to come to terms with it," Rose said.