Six bodies have been recovered from a fast food outlet set ablaze by an angry mob after an attack on a Shia mosque in Karachi, rescuers say.
Angry protesters set a KFC outlet on fire
"They were apparently trapped in the burning building," fire brigade chief Kazim Ali told the BBC News website.
Five people were killed and about 20 others wounded in the suicide attack on the Shia mosque in central Karachi.
There have been numerous acts of sectarian and criminal violence in Karachi in recent years.
Last Friday, a suicide bomber in the capital, Islamabad, killed 19 people and wounded nearly 100 in an attack on a shrine where hundreds of Shias had gathered.
Shia leaders in Karachi have announced three days of mourning and urged their followers to remain peaceful.
In another incident on Tuesday, one person was killed in an attack on a Sunni mosque in Karachi.
The victims of Monday's mosque bombing included two people believed to have carried out the attack and a policeman.
A third attacker was injured and is in hospital.
Soon after the blast angry protesters set fire to a branch of Kentucky Fried Chicken.
Two petrol stations and several cars were also attacked as news of the mosque attack spread.
"We were stopped from reaching the affected area by the protesters," Mr Ali said.
The BBC's Aamer Ahmed Khan in Karachi says the restaurant was attacked because of its proximity to the mosque. KFC outlets, closely identified with the US, are frequently targeted during anti-American riots in Pakistan.
Firefighters entered the building to discover four charred bodies, two each at the ground and first floors.
May 2005: 19 killed and nearly 100 wounded in Islamabad mosque attack
March 2005: 43 Shias killed in a bomb blast in Fatehpur, Baluchistan
Oct 2004: Car bomb in Multan kills 40 Sunnis
Oct 2004: 30 killed in a suicide attack on a Sialkot Shia mosque
May 2004: 20 killed in bombing of Shia mosque in Karachi
May 2004: 15 die in Karachi Shia mosque attack
Shortly afterwards, two more bodies were recovered from the freezer in the basement.
They had apparently frozen to death.
"Several eyewitnesses told us that there were 18 to 20 people inside the KFC when it was set ablaze," Mr Ali said.
"Most of them escaped by climbing up to the roof and jumping onto the adjacent building."
The dead were identified as KFC workers.
Mosque administrators across Karachi have been instructed to keep their doors closed during prayers. No vehicles are allowed to be parked around mosques at prayer times, police said.
Despite the new security measures, there was another attack on Tuesday, this time on a Sunni mosque in the Malir town area of the city.
Several armed men appeared around the mosque and opened fire, eye-witnesses said, leaving one person dead and several injured.
The area around Malir where the mosque is located has a mixed Shia-Sunni population.
In other parts of the city groups of men attacked and set light to vehicles, including the car of Qazi Hussain Ahmed, the leader of the six-party Islamic alliance, the MMA. He had been attending funeral prayers for leading local MMA politician Aslam Mujahid who was kidnapped and shot dead on Monday.
He was tipped to be the religious parties' candidate for Karachi mayor in local elections due in a few weeks.
Monday's violence started when three people walked into the Shia mosque and started firing in the air.
The Shia mosque was attacked when people had started to pray
"The bomber rushed to the spot where people had gathered to pray, and the next thing we heard was a loud explosion," mosque spokesman Shahzad Rizvi told BBC News.
"In the mayhem I heard the other two attackers begin firing."
Police are hoping to question the injured attacker currently undergoing treatment at a local hospital to find out who was behind the attack.
"He is still unconscious and we haven't had a chance to interrogate him as yet," chief of investigations Manzoor Moghul told the BBC News website.