KARACHI (Reuters) - A loud blast was heard from inside a military base in the Pakistan city of Karachi on Sunday, but police said it was not clear if it was a bomb.
"We are trying to check the cause of the blast. I cannot say," said senior police official Tahir Naveed.
Another police official said gunfire was also reported from inside the base. A witness heard a second explosion from the base.
Al Qaeda-linked Taliban militants, who have vowed to avenge the killing of Osama bin Laden by U.S. special forces, have carried out several attacks since his death on May 2.
(Reporting by Faisal Aziz and Imtiaz Shah)