Emergency services at the scene of the explosion
An explosion has struck a bus depot on the outskirts of the Pakistani city of Rawalpindi, killing at least eight people, police say.
At least another 17 people were injured in the attack at the Pirwadhai depot, city police officials said.
Rawalpindi police chief Nasir Khan Durrani told the BBC the blast appeared to be a suicide car bomb attack.
It comes on the day a major opposition rally was called off after the sacked chief justice was reinstated.
Interior ministry chief Rehman Malik said the bomber was probably deployed to attack the opposition rally, AFP news agency reported.
"We had prior information that there could be an attack during the 'long march' in Rawalpindi and Islamabad," he was quoted as saying.
"The people who did this are trying to destabilise Pakistan."
Militants opposed to Pakistan's support for US-led operations in Afghanistan have been held responsible for a string of bomb blasts across the country.
There were attacks on Sunday and Monday in Peshawar in north-west Pakistan on container terminals supplying Western forces.
Correspondents say the Rawalpindi depot, which serves the garrison city and the nearby capital of Islamabad, is close to a large market and the area is busy throughout the day.
Emergency services are at the scene and ambulances have been ferrying the injured to hospital.
A number of cars and roadside stalls have been destroyed in the explosion.
The blast comes as lawyers and opposition supporters across the country have been celebrating the government's decision to reinstate chief justice Iftikhar Chaudhry.
The protesters had been planning a major demonstration in Islamabad but called off the action.