At least 10 people were killed when a roadside bomb exploded close to a prison vehicle and a school bus in north-western Pakistan, officials say.
The remote-controlled device exploded in the Upper Dir district of North-West Frontier Province near Swat valley.
Officials said those killed by the blast included four schoolgirls and a number of policemen and prisoners.
Earlier, a suicide bomb attack on the main police complex in central Islamabad wounded at least 13 people.
The bombings came just over two weeks after more than 50 people were killed and 260 wounded in a suicide bombing at the capital's Marriott hotel.
They also happened as parliament met in a special session for a second day for a classified security briefing on Pakistan's internal security situation.
The joint session was called to try to help form a national consensus on how to tackle Islamic militancy and the surge in suicide bombings.
The blast targeting the prison van in Dir occurred shortly after the Islamabad attack.
Upper Dir is close to the Swat Valley, where troops are battling militants
Officials said a school bus which was driving past at the time was also hit.
"The van was carrying prisoners to jail after court proceedings when the roadside remote-controlled bomb went off," local mayor Sahibzada Tariqullah told the AFP news agency.
District administrator Sher Bahadur said 10 people were wounded.
Upper Dir district lies close to Swat and the border with Afghanistan, where security forces have been battling pro-Taleban militants since last year.
Pakistani security forces said they had detained 18 suspected militants in the valley during an operation on Wednesday, local media reported. Large quantities of arms and ammunition were also seized.
Air force jets have also bombed suspected Taleban positions in the Bajaur tribal region and in Swat.
Officials said at least 20 militants were killed, eight of them foreigners. There is no independent confirmation.
Footage of the bombed police complex in Islamabad
Earlier, a suspected suicide bomber partially destroyed an anti-terrorist squad building deep inside a police complex in Islamabad, injuring 13 people.
The explosion destroyed the front section of the red-brick structure and gouged a crater in the ground.
Police said a man delivered sweets to the reception area just before the blast. They are investigating whether there is a link.
The Islamabad blast destroyed part of the anti-terror squad building
The inspector-general of Islamabad police, Asghar Raza Gardezi, said the authorities would be looking into why a civilian vehicle was allowed past security checks into the compound.
Another police officer told the BBC that it had been fortunate that many of the officers stationed in the building had been guarding parliament and other areas of Islamabad at the time of the blast.
A spokesman for the Pakistani Taleban told the BBC the group carried out the attack in retaliation for army operations against it near the Afghan border.
The BBC's Barbara Plett in Islamabad says the fact that the attack occurred as lawmakers were discussing how to deal with Islamist militancy shows just how difficult their task is.
The attacks in Islamabad and Dir drew condemnation from Prime Minister Yousuf Raza Gilani, who promised those responsible would be brought to justice.
Our correspondent says the government had said it had strengthened security measures in the capital after the Marriott attack last month.