Eyewitnesses said that the youths boarded the bus -- which was coming from Anand Vihar towards ISBT -- near Kantinagar Chowk round 7.30 p.m.. When the bus was crossing an isolated area near Shastri Park in the Seelampur police station area, two of the youths took out knives and started threatening the passengers.

They snatched a bag containing Rs 40,600 from one of the passengers, Subhash Chandra Garg, who runs a garment shop in east Delhi. Garg said: ``I was trying to hold on to my bag without being too conspicuous. All my earnings in the last few days were inside, and I wanted to deposit it in the bank tomorrow.''

He added: ``Suddenly I realised that someone was pulling the bag from behind. I looked around to find one of the youths standing with a knife.''

The other members of the gang, brandishing kattas, joined in and went on a looting spree.

Though most of other the passengers did not have more than a few hundred rupees in their possession, one of them, Vipin Kumar Rai, lost Rs 2,500.

The ordeal of the passengers ended after the youths forced the driver to stop the bus just before the new Yamuna bridge and fled the spot.

None of the passengers sustained injuries, though a couple of them were assaulted when they tried to protest.