Twin suicide attacks seconds apart targeted the Pakistani military on Friday, killing 39 people in the second attack to hit security forces in the country's cultural capital this week.
The bombers walked up to Pakistani army vehicles in the densely populated R A Bazaar area of Lahore, blowing themselves up as people sat down to eat before the main Muslim weekly prayers were to begin, a senior official said.
The attacks underscored the rising volatility in Lahore, where security targets have been subject to attacks blamed on Taliban and Al-Qaeda-linked militants opposed to Pakistan's alliance with the United States.
Mohammad Nadeem, a young man in his 20s wearing traditional white shalwar khamis with bloodstains down the front, said he was saying prayers in the mosque when he heard the first blast and rushed out.
"I saw people crying and running in different directions. They were panicked," he said.
"The second blast took place very near a military vehicle. I sensed real danger and started running.
"There were scenes of destruction in nearby restaurants and shops. There were broken chairs and tables and other items lying everywhere on the ground."
The bombers targeted the cantonment of Lahore, an area home to army officials and military installations, as well as hospitals and schools run by the military. But civilian homes, shops and restaurants are also in the area.
The army cordoned off the tree-lined street where there were shops and a mosque, preventing access to journalists as ambulances raced through the city of eight million to ferry the dead and wounded to hospitals.
Pakistani authorities said 39 people were killed, including five soldiers according to security officials speaking on condition of anonymity.
"We have the heads of both the bombers. There was an interval of 15 seconds between the two attacks. They were on foot. Their target was army vehicles," police official Chaudhry Mohammad Shafiq told reporters.
"Thirty-nine people were killed and 95 wounded in the attacks," Tariq Saleem Dogar, the Punjab provincial police chief, told reporters on live TV.
"We have collected concrete technical evidence, which will help identify the attackers," he added.
A wave of suicide and bomb attacks across Pakistan has killed more than 3,000 people since 2007. Blame has fallen on Taliban and Al-Qaeda-linked militants.
On Monday, a suicide car bomber destroyed security offices used to interrogate suspected militants in an upmarket Lahore neighbourhood, killing 15 people in an attack claimed by Pakistan's mainstream Taliban faction.
Lahore, Pakistan's historic cultural capital and home to many military and intelligence top brass, has been repeatedly in the militants' sights, with eight attacks killing more than 170 people in the city over the past year.
Violence is usually concentrated largely in the lawless northwest border area with Afghanistan, but analysts have warned that extremism is taking a hold in Punjab, Pakistan's most populous province, which has Lahore as its capital.
Washington has put Pakistan on the front line of its war on Al-Qaeda, stepping up pressure on the military to act against Islamist militants and calling its border area with Afghanistan the most dangerous place on Earth.
Pakistan's military claims to have made big gains against Taliban and Al-Qaeda strongholds over the past year, following major offensives in the northwestern district of Swat and the tribal region of South Waziristan.
This year there had been a marked decline in violence by Islamist militants in Pakistan after a significant increase in bloodshed in late 2009.
Officials have linked the reduction to the suspected death -- still not confirmed -- of Pakistani Taliban leader Hakimullah Mehsud and military offensives that have disrupted militant networks.
Washington says militants in Pakistan's semi-autonomous tribal belt are supporting the war in Afghanistan, where more than 120,000 NATO and US troops are battling a deadly Taliban insurgency.