At least one person has been killed in a suicide attack on a bus carrying government employees in the Pakistani city of Rawalpindi, police say.
The blast also injured about 29 people, four of them critically. It is said to have taken place at a main intersection in the northern garrison city.
The bus is reported to have belonged to Pakistan's main weapons manufacturer.
No group has yet claimed responsibility for the attack. The past year has seen a sharp increase in suicide bombings.
Nasir Khan Durrani, Rawalpindi's police chief, initially said at least five people had been killed, but later revised that figure to one on the basis of new information from the hospital.
"It was apparently a suicide attack as the man on the bike struck the bus head on and exploded," Mr Durrani told the BBC earlier.
The BBC's Syed Shoaib Hasan in Islamabad says the attacks come despite unprecedented security measures in Rawalpindi and the capital Islamabad, just a few kilometres away.
Security has been tightened around all major cities as Pakistan continues its offensive against Taliban militants in the north-west. The Taliban have threatened attacks in response.
The Pakistani army has its headquarters in Rawalpindi.