At least 10 people have been killed and 30 injured in a bomb explosion at a market in the Pakistani city of Quetta, officials say.
Reports said that the bomb exploded near an army truck in the city, the capital of Balochistan province.
Both soldiers and civilians were among the casualties, police said. No one has yet said they carried out the attack.
Information Minister Sheikh Rashid Ahmed said "enemies of Pakistan" were behind it.
"The people responsible will not go unpunished."
'Political motives'
The explosion occurred in the centre of a business district.
Bomb disposal officials said the bomb, which was attached to a bicycle, could have been up to 20kg in weight.
"Thank God it was Friday and the bazaar was closed," Quetta's mayor, Moahmmed Rahim Kakar told the BBC, "otherwise the death toll would have been very high."
Police are investigating whether the bomb was a timed device or remote-controlled.
Television pictures showed chaotic scenes as the injured were loaded into minibuses and ambulances.
Vegetable seller, Ali Mohammad, told the AFP news agency: "Nobody knew what happened. We thought it was an earthquake. There were dead bodies and wounded and blood was splattered."
The site of the explosion is close to a compound where military trucks are parked but it is not clear if the security forces were the target of this attack.
Security has deteriorated in Balochistan in the last 12 months.
The BBC's Aamer Ahmed Khan in Karachi says there have been more than 30 bomb attacks in Quetta, but none have been as deadly as Friday's blast.
Quetta police chief Parvez Rafee Bhati said that attack had "political motives" and that "nationalist elements" opposed to the federal government were behind it.
A little-known group, the Balochistan Liberation Army, has claimed responsibility for some of the bomb attacks in the province this year.
Quetta has also been a centre of operations for Pakistani security forces tracking al-Qaeda members.
In September they arrested an alleged senior al-Qaeda operative, Sharif ul Misri.
The Quetta mayor said Friday's blast may have been in response to operations against al-Qaeda in the area.
is going on man.and some people blame us that we are terrorists 
our peoples are dieng are'nt they human being?or the muslims are born for get killing who are behind in blast every one knows that 
and shaire lahore u r absolutly right allah is with us and he will protect us against 
