Aftermath of two bomb blasts outside a munitions factory in Wah
At least 63 people have been killed and dozens injured in twin suicide bombings outside Pakistan's main munitions factory in the town of Wah, police say.
The attack is the deadliest on a military site in Pakistan's history.
Police say one man is in custody for the attack, which occurred some 30km (18 miles) north-west of Islamabad.
A spokesman for the Pakistani Taleban said they had carried out the attacks, which he said were a response to army violence in the country's north-west.
Speaking to the BBC, Maulvi Umar of the Tehrik-e-Taleban Pakistan said the bombings in Wah were in retaliation for the deaths of "innocent women and children" in the tribal area of Bajaur.
He said more attacks would take place in Pakistan's major urban conurbations unless the army withdrew from the tribal areas.
Pakistani Prime Minister Prime Minister Yousef Raza Gilani promised to punish the perpetrators.
US President Bush later telephoned Mr Gilani to pledge his support in tackling what he called terrorist attacks.
The leaders "reaffirmed their mutual support for going after these extremists that are a threat to Pakistan, the United States and the entire world," a White House spokesman said.
Wah is a strategically important town normally under heavy security as it is home to a large industrial complex producing conventional arms and ammunition, correspondents say.
The first blast took place outside the gate of the factory as workers were leaving work during a shift change.
Minutes later, another blast took place at a market nearby another gate of the same factory.
Local police chief Nasir Khan Durrani told the BBC: "Many others have been injured and we expect casualties to rise."
Mr Durrani said none of the dead were military personnel.
Mohid Ahmed, a student from Wah, was on a tour of the ordnance factories and witnessed the immediate aftermath of the blast from his bus.
"There was smoke, bodies and blood," he told the BBC.
"Those who were left alive were in great suffering. I saw a man clutching his leg and crying in pain and asking for help."
On Tuesday, 32 people were killed in a suicide attack on a hospital in the northern town of Dera Ismail Khan.
The BBC's Syed Shoaib Hasan says it is the second recent direct attack on a Pakistani military installation.
Last September, 17 officers and soldiers were killed in a suicide attack on a special forces base in the nearby town of Tarbela-Ghazi.
The ordnance factories at Wah lie on the road into Pakistan's troubled north-west, where fighting between security forces and Islamic militants has raged in recent weeks.
Established in the early 1950s, it is a sprawling complex manufacturing everything from tanks and small arms to artillery shells.
Militants have often threatened to increase the level of violence unless the army pulls back from tribal areas close to the border with Afghanistan.
Pakistani politicians are, however, currently more preoccupied with political issues after the resignation of President Pervez Musharraf on Monday, the BBC's Charles Haviland in Islamabad says.
Mr Musharraf, a key ally of President Bush's "war on terror" stepped down after nine years in power to avoid being impeached.