A suicide bomber blew himself up at a checkpoint in northwest Pakistan as officials tried to rescue a peace deal to contain Islamic militants in the lawless border region.
The bomber targeted a security checkpoint in North Waziristan, killing three Pakistani soldiers and one civilian.
Tuesday's attack is the latest in a wave of deadly violence following the breakdown of a peace deal between the Pakistan government and pro-Taleban militants. More than 70 people have died in attacks by suspected militants over the past few days.
The recent violence is thought to involve revenge attacks following last week's government assault on a radical mosque in Islamabad, which left scores of militants and a leading cleric dead.
Pro-Taleban militants pulled out of the deal on Sunday after accusing the Pakistani government of violating it by deploying more troops in North Waziristan and launching attacks.
Authorities are trying to save the deal, despite concerns by the United States that it has provided a safe haven for Islamic extremists.
President Pervez Musharraf insists the pact, in which the military scaled back its operations in return for pledges from tribal leaders to contain militancy, offers the best long-term hope of pacifying the region.
Some information for this report was provided by AFP, AP and Reuters.
