Troops have surrounded and attacked a stronghold of a leading militant in the district of Swat in northern Pakistan, local police say.
Troops have been airlifted to positions on the hilltops
The pro-Taleban militant, Maulana Fazlullah, said earlier this week that he was leaving the area.
On Thursday an attack in the main town of Swat left at least 17 soldiers and a number of civilians dead.
Swat is one of a number of areas near the Afghan border where militants have been gaining control in recent months.
A BBC reporter in Swat says that the fighting has now stopped. Our correspondent says the reason for this is unclear, as there have apparently been no negotiations between the two sides.
A spokesman for Maulana Fazlullah said that one of his men had been killed in the fighting, and our correspondent says that there are unconfirmed reports that three civilians are among the dead.
Witness described heavy fighting earlier in the day.
"Heavy weapons are being fired, and there have been more than a dozen explosions. I can see black smoke rising from the hills," a local journalist told the BBC news website.
Local people are reported to be fleeing the area.
Eyewitnesses say the firing started when troops were airlifted to positions on the hilltops surrounding Maulana Fazllullah's stronghold.
He said on Wednesday that he was moving to another district, Kohistan.
"The security forces attacked a building where Maulana Fazlullah had been appearing in recent days to urge his followers to target the Pakistan army, police and other security forces," a police official in the main town of Swat, Mingora, said, the Associated Press news agency reports.
On Wednesday the army deployed 2,500 more troops in the area to combat rising militancy.
Maulana Fazlullah has reportedly used radio broadcasts to call for jihad, or holy war, against the Pakistani authorities.
In July at least 10 Pakistani soldiers were killed in a militant attack in Swat.
It was part of a wave of attacks on the army in response to the security forces' storming of the radical Red Mosque in the capital, Islamabad that left more than 100 people dead.