Investigators try to piece together Karachi car bomb evidence

US and Pakistani investigators are continuing their search of the American Consulate in Karachi after a car bomb killed 11 people.

A previously unknown group has claimed responsibility for the massive blast on Friday which also injured 45 others.

Karachi newspapers received a fax message claiming responsibility in the name of "Al-Qanoon," or The Law, although US authorities have been unable to prove its authenticity.

The message said the attack was a "preview with more to follow" and was part of a holy war against the United States and its "puppet ally," the Pakistani government.

The widespread devastation is making it difficult for investigators to piece together events leading up to the bombing, even which vehicle contained the explosives.

Initial reports indicated a suicide attacker was responsible, but police say they are also looking at the possibility that the bomb was hidden in a car carrying a driving school instructor and three female students, then set off by remote control.

A US Consulate spokesman, said a number of American teams were coming into Karachi to investigate the crime scene and evaluate structural damage to the building. Additional security is also arriving.

"We are looking for information that will be useful in identifying the perpetrators and finding evidence that would bring the criminals to justice," the spokesman said.

The United States has promptly closed its consulates in Karachi, Lahore and Peshawar, as well as the American Centre in Islamabad.

A State Department official says a decision will be made soon whether to reopen them on Monday.