Exposing chinks in the security of Tihar Jail, 12 undertrials escaped on Wednesday when they were being taken to be presented before a special court.
Two of them were soon apprehended.
Delhi Armed Police personnel were escorting the undertrials, lodged in Asia's largest prison, to the court inside the same jail premises.
When one group of policemen were handing them over to another, the 12 managed to given them the slip, police sources said.
While police managed to nab two of them soon, 10 were still on the run.
A major combing operation had been launched in the area and additional forces deployed at all exit points from the city, the sources said.
Each of the undertrials had one or two cases registered against him, they added.