A lottery ticket seller in southern Spain has been hailed as a hero after he spent about six hours ferrying rescuers and victims around on his quad bike after the train collision that killed at least 41 people and injured dozens of others.

Gonzalo Sánchez, 43, was at home in the small town of Adamuz when the town’s WhatsApp group alerted to reports of a train that had derailed nearby.

Sánchez sprang into action, grabbing a few tools and heading to the site in his car. He was among the first to arrive at the scene. “It’s something you hope to never come across in your life,” he told the broadcaster Cadena Ser. “The images are very shocking on television, but it’s worse on the ground.”

He began doing what he could to help, soon learning from passengers that a second train had been involved in the collision. “It was pitch black, and you couldn’t see a thing. Nobody had noticed there were more train cars and people further down,” he told El País.

The overturned Iryo train on the tracks in Adamuz after the collision. Photograph: Carlos Álvarez/Getty Images

Officials later said a high-speed train carrying about 300 Madrid-bound passengers had derailed, sending it into the path of an oncoming train carrying about 200 passengers. The impact knocked the first two carriages of the oncoming train off the track, sending it plummeting down a 4-metre (13ft) slope.

Alongside rescue workers, Sánchez raced to the site of the second train, about 1km away, taking in the scenes of twisted metal, scattered debris and victims pleading for help. “The scene on either side was indescribable, terrible, terrifying,” he said.

Complicating matters was the rugged terrain. The collision had taken place in a remote area where the railway tracks were hemmed in by ridges that rose up on either side.

Sánchez realised the all-terrain vehicle he had at home could be of use. “I told them I had a quad bike and that it might be useful in terrain like that. And the rescue workers said: ‘Yes, go ahead’,” he said.

Once back on site, this time with his quad, he spent hours carefully transporting firefighters, paramedics and police along the narrow space that lay next to the tracks, as well as carrying passengers – some of whom were injured – to safety.

It was an echo of the outpouring of support in Adamuz, where residents travelled to the site to help, opened their homes to victims and handed out supplies and support at a hastily erected response centre.

Sánchez said he continued to ferry people on his quad until 2am, when a minor bump against the door of an ambulance left it unusable. As Spain woke up to news of the devastation on the outskirts of his town, interview requests began pouring in for the man that media were calling the “quad hero” of Adamuz.

Sánchez shrugged off the attention, pointing instead to the hundreds of rescuers who worked throughout the night to help the hundreds of people affected by the collision. “I did what anyone would have done when something like that happens,” he said.

King Felipe and Queen Letizia visited the crash site on Tuesday, where two cranes and other heavy machinery were being used to clear the debris and recover at least three bodies still trapped in the wreckage.

Spain’s socialist-led coalition government warned against rushing to conclusions as the country began three days of national mourning.

King Felipe VI and Queen Letizia of Spain at the command post in Adamuz. Photograph: Carlos Álvarez/Getty Images

The interior minister, Fernando Grande-Marlaska said “all hypotheses” regarding the causes of the deadly crash remained open. He added that the laboratory tests would need to be carried out on the section of track where the derailment occurred, and that the rolling stock of the train that came off the line, causing the accident, would also need to be examined.

“There’s an initial point where the derailment is believed to have occurred,” the transport minister, Óscar Puente, told Cadena Ser on Monday night.

“Now we have to determine if it’s the cause or the consequence. It’s not a trivial matter, and it won’t be quick or easy. We’ll have to send the track to the lab; we have to determine what happened. At this point, nothing can be ruled out.”