A man who was first on the scene after a fatal crash has offered his support to the survivors.

Dawid Rzepka was on his way to Luton Airport on the M25 this morning when he saw a Peugeot 3008 that had collided with a barrier at j18 for Rickmansworth.

Realising what had happened, he reversed up the motorway and ran to the car.

He found the driver on his phone to the paramedics and a woman who was trying to stop the bleeding from a head injury suffered by an 18-year-old.

Mr Rzepka, 32, from Bicester in Oxfordshire, remembers saying “everything will be okay” before he took over from the woman and tried to give first aid.

Paramedics soon took over and said they needed to take the 18-year-old man to hospital.

But despite the best efforts of everyone at the scene, the 18-year-old died.

An 11-year-old boy was also travelling in the car with the man and woman, who were in their 30s.

The driver suffered minor injuries while the other two passengers were not injured.

Speaking to the Watford Observer, Mr Rzepka said: “I just tried to help any way I could. When I saw the crash, I rushed to help. I couldn’t believe that no one else was stopping but then a lorry driver who said he was an ex-soldier did and said he could offer first aid.

“The paramedics arrived and took over. We helped to put him on a stretcher.

“I just want to tell the family that I tried and that if they need help, they have my support. I am thinking of them."

Police are appealing for witnesses to come forward and are keen to trace three vehicles.

These are an articulated lorry with a light-coloured cab, green side curtains, and white rear doors. The second vehicle is another articulated lorry cab with a flatbed on the rear which was carrying a number of dark red building bags.

The third vehicle police would like to trace is a 3.5 tonne flatbed truck with a high level rail or cage.

Police are also seeking any dashcam footage that may have been caught of the crash, which they believe involved a single vehicle.

The motorway was shut for around five hours between j17 and j18 while police investigation work was carried out.

Anyone with any information is asked to email the Forensic Collision Investigation Unit on FCIUsouth@Herts.pnn.police.uk, or call 101, quoting ISR 126 of August 20.