When the automatic system failed, ground technicians at the pad had to manually send the command to activate the SAS — the launch escape system (Sistema Avariynogo Spaseniya) — literally in the final seconds before the fire engulfed the entire rocket.
The escape system — a set of small rocket motors mounted on a tower above the cabin — instantly tore the descent module with the crew away from the burning rocket and carried it to a safe altitude. The crew experienced severe g-forces in the process.
Just a few seconds later, the remaining rocket exploded on the pad in a huge fireball — exactly what Titov later described as the sight of the spot where their launch vehicle had stood only moments before.
From the flight transcript
We felt a powerful jolt, and suddenly we were some distance from the pad — a few seconds later, where the rocket had stood, there was nothing but fire.
Wikipedia: Launch escape system · NASA History — Apollo — full list on Escape and Backup Systems in Spaceflight