In a daring heist, a gang on Sunday morning at a gunpoint looted passengers of cash and valuables and assaulted some of them aboard the prestigious New Delhi-Patna Rajdhani Express in Bihar's Buxar district, the police said.

A dozen men barged into three coaches of the train near the Buxar railway station, about 125 km from here, and threatened to shoot the passengers if they tried to resist the robbery, the passengers told the police.

At least seven Government Railway Police (GRP) official -- a Sub Inspector and six constables -- were suspended and an FIR was registered at the Patna railway station after the angry passengers protested here.

The passengers told the police that the robbers boarded the train somewhere between Mughalsarai and Buxar. After looting them, they pulled the chain to stop the train and fled.

Patna Rail Superintendent of Police Jitender Mishra said an inquiry has been launched into the incident and the criminals would be arrested soon.