A suicide bomber killed at least three other people when he detonated a powerful bomb at a Shiite Muslim mosque in the Pakistani city of Lahore, police said.
The blast on Sunday was the third deadly attack in the past 10 days as suspected sectarian violence spiralled between the country's majority Sunni and minority Shiite Muslims.
Police said a suicide bomber carrying the explosives tried to get inside the eastern city's Kashmiryan Mosque, where worshippers had gathered for evening prayers.
"When security guards stopped him he opened fire and blew himself up, killing two security guards," local police officer Zahir Uddin Babar said.
The bomber's headless body was lying at the blast site in the Mochi Gate area of the walled city, according to witnesses. Police said a 12-year-old boy also died in the blast.
Pieces of human flesh were placed on a stretcher and transported to local hospital in ambulances, witnesses said. Police surrounded the mosque and hundreds of people had gathered outside.
Four people were injured in the blast, but a hospital official said they were out of danger. Several others with minor injuries have already been discharged, he said.
The bombing appeared to be the latest in a bloody cycle of revenge attacks on Shiite or Sunni Muslim targets which have killed more than 70 people in the past 10 days.
A suicide bomb attack on a Shiite mosque in the eastern city of Sialkot on October 1 killed 30 people. It was followed six days later by a car bomb attack on Sunni radicals in the central city of Multan in which 41 died.
On Saturday unidentified gunmen murdered two Sunni Muslim clerics including a prominent religious scholar Mufti Jamil in the southern port city of Karachi.
Some 10,000 mourners attended the funeral of Jamil who was buried in Karachi late Sunday.
Punjab provincial governor Khalid Maqbool condemned the blast in Lahore. "Those who play with the lives of the people have no religion," he said.
Information Minister Sheikh Rashid described the recent spate of attacks as a conspiracy to trigger Sunni-Shiite violence.
"There is no Shia-Sunni rivalry in the country and leaders of both sects know that it is conspiracy by those who want to plunge the country into instability," he said.
The bomber struck at 5:55 pm (1255 gmt) when people were preparing for evening prayers, eyewitness Abbas Kazmi said.
He said a man aged between 25 and 30 carrying a bag force his way into the mosque. He went into the hall and when the guards grabbed him he detonated the device.
Senior police officer Aftab Ahmed Cheema lauded the role of the guards saying, "they sacrificed their lives and foiled an attempt to cause heavy casualties" among the worshippers.
He said they had found the bomb with the help of a metal detector.
Bomb disposal unit commander Allah Rakkha told reporters that pieces of a hand grenade had been found at the site of the blast.
The grenade appeared to be Russian-made, he said, adding that investigations had been launched to determine the type of explosive used.
Most of Pakistan's Sunni majority and Shiite minority live together in peace. But fanatics have been e3ngaged in bitter tit-for-tat violence since the 1980s. The conflict has so far cost more than 4,000 lives.