A grenade followed by a powerful car bomb exploded outside a Christian church, injuring at least 13 people in the first instance of anti-Christian violence in more than a year.
Two men on a speeding motorcycle hurled the grenade at the Pakistan Bible Society's Christian Reading Library, next to the Trinity Church, in central Karachi's crowded Saddar bazaar, injuring no-one but drawing crowds, security officials said Thursday.
The car bomb went off some 15 or 20 minutes later as employees of the library and church gathered outside along with several policemen.
"The blast was timed to cause maximum damage. It was a very close shave," a senior Karachi police officer told AFP.
"The policemen and the employees were lucky that they were standing away from the bomb-fitted car, otherwise the toll could have been higher."
Interior Ministry official Brigadier Javed Cheema, who heads the Crises Management Cell, said 13 people were wounded.
"Thirteen people were injured but no one has died. A majority of the injured had minor wounds," Cheema told AFP.
Bomb disposal squad official Kashif Jalal said the library was targetted with a grenade and not a firecracker.
Jalal said up to nine kilogrammes of explosives were used in the car.
Deputy police superintendent Irshad Sehar was near the church when the attack happened.
"I saw two motorcyclists stop by the Christian library and one rider stepped down and hurled something towards the library and there was a blast," he said.
Irshad and two other policemen were injured, along with three paramilitary rangers and two Christians.
Witnesses said the car explosion sent shrapnel through the crowd.
"While we were standing in the compound, suddenly we heard a big bang and shrapnel struck the crowd causing injuries and panic," said library manager Shazeb Shamoon.
"I was busy in my routine work inside the library when a deafening blast occurred and a glass splinter hit my face and shoulder and I fainted," library employee Peter Pervez told AFP.
Library assistant Alfred Fredricks said he emerged from the library after the grenade blast and was helping police when the car exploded.
"I saw a vehicle fly in the air with a huge blast," he said.
One of the injured paramilitaries, Mohammad Iqbal, who was on duty at a nearby police post, said he and his colleagues tried to chase the motorcyclists but they escaped.
The attack appears to be the first anti-Christian strike since 2002, when five attacks on Christian institutions left 25 people dead.
Those attacks were blamed on Islamic militants furious at the government's support of the US-led ouster of the Islamic Taliban regime in neighbouring Afghanistan.
In March 2002 a suicide bomber attacked a church in Islamabad being attended by diplomats and in August gunmen killed six people at a school for foreign missionaries' children in Murree.
In the same month four people were killed in a grenade attack on a hospital chapel in Taxila.
Seven Christian welfare workers were shot dead in their office in Karachi in September 2002 and three worshippers were killed in a Punjab village church on Christmas Day that year.