All schools and universities have been closed across Pakistan a day after suicide bombers attacked an Islamic university in the capital, Islamabad.
Four people died and at least 18 were wounded in the twin blasts at the International Islamic University.
The Taliban claimed the attack and said there would be more violence unless the army ended its offensive in the tribal areas of South Waziristan.
Meanwhile, at least four people died in more intense fighting in that region.
Pakistani troops are battling to gain control of the key Taliban-held town of Kotkai, but say they are meeting fierce resistance.
A Taliban spokesman said 40 soldiers had been killed in an attack on a security post near the town, but the army gave a much lower figure.
The army said it had killed 90 militants since beginning its offensive on Saturday.
Because of reporting restrictions, it is extremely hard to find out what is going on in South Waziristan.
The fighting has caused tens of thousands of civilians to flee the area.
‘Sense of loss’
Wednesday’s attack was the first since the army launched its offensive against the Taliban in South Waziristan.
The militants have threatened more such attacks if the army continues its offensive.
Following the attack, Pakistan’s Interior Minister Rehman Malik said that Pakistan was now in what he called a state of war.
The government has ordered the closure of schools, colleges and universities to prevent them from being targeted by suicide bombers.
Some students said they were scared to go to classes.
“It’s really a tragedy for us and there’s a real sense of loss with the acts of terrorism,” Islamabad student Shehzeen Anwar told the BBC.
“Students are terrified and they’re afraid to go out. Roads are almost empty and people are staying at home.”
Earlier, schools run by the armed forces and the government – and some public schools – closed for a week as a result of the South Waziristan operation.
The BBC’s M Ilyas Khan, in Islamabad, says the present closure is indefinite.
However, schools, colleges and universities may reopen next week if the security threat decreases, he says.
A wave of attacks on Pakistani cities has killed more than 180 people during the month of October alone.