The aftermath of the bomb attack on the university
Two suicide bombers have killed at least four people at a university in the Pakistani capital Islamabad.
At least 18 people were wounded in the twin blasts at the International Islamic University.
The attack is the first since the Pakistani army began its offensive against militants in South Waziristan, in the country's north-west.
In a telephone call to the BBC, a senior Taliban commander has claimed his movement was behind the bombings.
Qari Hussain, the man reportedly responsible for training Pakistani Taliban suicide bombers, said his organisation now considered all of Pakistan to now be a war zone.
AT THE SCENE
Orla Guerin BBC News, Islamabad
One of the blasts happened outside the office of the professor of Sharia law. The blast was so powerful that it punched a massive hole in the wall of that office.
Rubble and masonry were littered on the floor, as well as some shoes - it's unclear whether these belonged to the bomber or one of his victims.
One student said the sky went dark when the explosion happened, that some people ran away in fear while others tried to help the victims.
Pakistan was hit by a wave of bombings by Taliban and al-Qaeda supporters in the days before the assault began.
Security has been stepped up in recent days, and many schools in Islamabad and other big cities were told to close for the week.
In South Waziristan itself, fierce fighting is continuing for a fourth day as Pakistani troops battle to gain control of the key Taliban-held town of Kotkai.
The blasts at the International Islamic University hit the women's cafeteria and the Islamic law department.
Police superintendent Abdul Ghafar Quaiserani said the two suicide bombers struck at about the same time.
'State of war'
One student, who e-mailed BBC News, said gunfire had preceded the explosions:
"There were gunshots at first and then two explosions one after the other. One was just outside the gate of the girls' cafeteria and the other one targeted the head of the department for Sharia studies.
"I was near that office. Two of my friends were injured, they were taken to the hospital. I am in shock. Now we are not even safe in our universities."
President Asif Ali Zardari and Prime Minister Yousuf Raza Gilani condemned the blasts.
And Interior Minister Rehman Malik said: "We are in a state of war. They will make every effort to destabilise the country.
"These so-called Islamists are enemies of Islam and enemies of Pakistan."
The Associated Press says the International Islamic University was established on the outskirts of the city in the 1980s and has more than 12,000 students - nearly half of them women, many from abroad.
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