Detectives have appealed for witnesses and anyone with dash cam footage to come forward after a teenager and grandfather died when their car was hit by a train at a level crossing.
William Hallett, 15, and his 71-year-old grandfather Barry Hearnshaw were pronounced dead at the scene in Barns Green, near Horsham, West Sussex, after the collision at around 8.40am on Saturday.
British Transport Police detectives said on Thursday they now want to speak to any motorists or pedestrians who were in the area at the time.
Detective Inspector Darren Gough said: "My thoughts remain with the family during what must be an incredibly difficult time. My team of officers continue to work hard to establish exactly what happened in the moments leading to this awful incident.
"Since Saturday's incident, a number of people have contacted us and I am grateful for their help. However, I would now like to appeal to anyone else who was in Barns Green on Saturday morning and hasn't yet spoken with police.
"In particular, I am looking to hear from motorists who may have dash cam footage of Barns Green, or Barns Green level crossing, on Saturday morning."
In tributes on Tuesday relatives described Will as a "handsome, intelligent and extremely active" teenager who loved football, was a Chelsea Football Club fan and wanted to be a pilot. He played for Horsham Sparrows and attended Tanbridge House School.
Mr Hearnshaw was remembered as "devoted" husband, father and grandfather, who dedicated himself to charity work after retiring as a headmaster.
He worked for Cordeaux High School and Deighton Close School in Louth, Lincolnshire, and Muntham House School in Barns Green.
On Monday a steady stream of mourners was visiting the roadside near the level crossing to leave flowers and pay their respects.
Signed rugby and football shirts, cards and other gifts were also left at the scene and a book of condolence was set up in nearby St Nicolas Church, Itchingfield.
Anyone with information should contact police by texting 61016 or calling 0800 40 50 40 quoting 146 of 17/02/2018.