At around 3:15 in the morning, driver Özdemir Süer guided the Civan Turizm coach east along the D-100. Ahead, stationary on the roadside, sat a tanker truck that had broken down with a shaft malfunction. The truck, driven by Mustafa Filik, was carrying nitric acid. The collision happened in darkness. The tanker ruptured, and the acid spilled across the road and into a puddle at the roadside. The fumes were immediate and acrid. Inside the bus, sleeping passengers woke to what they believed was the smell of fire. Panicked, they moved to escape — a completely natural response. They had no way of knowing what had actually spilled outside. When they stepped off the bus, their feet and legs came into contact with the acid on the ground.

What followed was a sequence of tragedies built on misunderstanding. The passengers who left the bus and felt the burning of the acid on their skin looked for water — the instinctive remedy for any burning. There was water nearby, mixed into the puddle that the spill had already contaminated. Those who waded in, seeking relief, faced worse exposure. Eighteen people died at the scene. Seven more — including truck driver Mustafa Filik — died later from their injuries at Adapazarı State Hospital, bringing the toll to twenty-five. Among the injured who survived were seventeen others, including citizens of the United States and Lebanon who happened to be aboard that bus, and the driver Özdemir Süer himself. First responders came from Kargalıhanbaba village and from the 476th Light Transportation Battalion stationed in Hendek — soldiers who arrived to find a scene that was unlike anything in an ordinary emergency.

The passengers on the Sinemalı Civan were people in transit — the ordinary population of long-distance bus travel: people going to work, to family, to a destination they had chosen. The presence of passengers from the United States and Lebanon suggests the bus served an international route or carried travelers moving between major cities. Their names are not recorded in the available sources. What is recorded is the scale of what was lost: twenty-five people whose families would have been waiting for them, twenty-five lives interrupted at 3:15 on a summer morning on a highway in Sakarya Province. They were not statistics when they boarded that bus, and they are not statistics in the memory of the community that buried them.

The eighteen who died at the scene were buried in a pit dug by villagers ten meters from the accident site, by necessity, in the hours after the crash. The village imam conducted the funeral prayers there. In the years that followed, the families of those killed came to that place and built something permanent: a memorial tomb called the Traffic Martyrs' Memorial Cemetery — Trafik Şehitleri Anıt Mezarlığı in Turkish. The word şehit, meaning martyr, carries weight in Turkish culture that the word 'victim' does not quite match; it suggests someone whose death carries meaning, someone to be remembered with honour rather than only mourned with grief. The families chose that word deliberately. The memorial stands near Kargalıhanbaba today as a place of remembrance beside a highway that millions of travelers still use, almost all of them unaware of what happened there before dawn in the summer of 1965.