Police said they suspected anti-Western Islamic militant groups were responsible. There have been a number of militant attacks in Karachi on Western targets in recent years.
The powerful blast struck at about 8.45am, as commuters were heading to shops and offices in the crowded downtown area of Karachi, Pakistan's business hub.
The blast occurred about 100 yards from the Sheraton hotel, where the England cricket team is due to stay when they play Pakistan in a one-day match on 15 December.
Mushtaq Shah, Karachi's police chief, told reporters the bomb was concealed in a car parked outside the restaurant. Police explosives expert Mohammed Iqbal said the bomb was made from 11 pound) of homemade explosives and detonated by a timer. The car containing the bomb was blown to pieces, leaving a crater six feet across. Officers said the KFC restaurant, part of the global American fast food chain, was the apparent target.
"We are trying to get information about that person who parked the explosive-laden car outside KFC," Manzoor Mughal, a senior police investigator, said. "We are also trying to trace the owner of the car."
Mughal said the blast also damaged the offices of three Pakistani banks. One foreigner of unknown nationality was among the injured, but was released from a hospital after being treated, he said.
There were no immediate claims of responsibility for the blast, although Karachi has been the target of a number of bombings in recent months that have killed more than a dozen people. Police said they tightened security in the city and were searching for clues about those behind the attack.
Mughal wouldn't identify any suspects, but said members of three militant groups who police have been cracking down on remained at large.
"We have arrested most of the members of Jundallah, Harkat-ul Mujahedeen al-Almi, and Harkat-ul Mujahedeen, but some members are still at large and any of them could be involved," Mughal said.
He said investigators from military intelligence were hoping to glean clues from security cameras installed near the bomb site.
"So far we only know that the bomb was in a Suzuki car," Mughal said.
Hundreds of people gathered at the bomb site in the area of government offices and luxury hotels. The blast was powerful enough to damage windowpanes at the Pearl Continental Hotel, which is popular with foreign tourists and businesspeople.
A security guard in the hotel parking lot was hurt by a piece of flying metal, said a member of the hotel staff, Mohammed Arif.
Karachi, Pakistan's largest city, is a center of Islamic militancy, and previous bombings in the city have been linked to extremists opposed to Pakistani President Gen. Pervez Musharraf's close ties to the United States.
Pakistan's information minister, Sheikh Rashid Ahmed, condemned the blast, calling it the work of the "enemies of Pakistan."
The attack came three days before Pakistan is to host a conference of international donors to raise funds for victims of the devastating 8 October earthquake that killed about 86,000 people in the country's northwest and in Pakistani-controlled Kashmir. Hundreds of US and other foreign troops are in the country helping with quake relief.
The KFC restaurant occupies the ground floor of a government office building housing the Pakistan Industrial Development Corp. Firefighters prevented the blaze from spreading to other parts of the building.
In September, bombs struck KFC and McDonald's restaurants in Karachi, injuring three people in attacks believed linked to a nationwide strike called by a hardline Islamic coalition opposed to Musharraf.
A KFC restaurant in Karachi also was burned in May, killing six workers inside during an outbreak of religious violence between Sunni and Shiite Muslim groups in the city.
Other violence in Karachi in recent years included two attacks against the US Consulate and car bomb in May in front of the city's Sheraton Hotel that killed 11 Frenchmen.Reuse content