It's likely that Ahmed Abdi Godane, leader of Somalia's al-Shabab extremist group, was killed in a U.S. airstrike on Monday, but the group isn't saying, and U.S. officials can't confirm it.

Security sources quoted by AFP said it was likely Godane was killed in the airstrike. "We believe that the Shabab leader is dead, though we don't have his body. Most probably he is dead," a senior Somali security official told the news agency.

Abu Mohammed, an al-Shabab commander and spokesman, told the Associated Press that Godane was in one of two vehicles hit by the U.S. airstrikes, but would not say whether he was one of the six people killed.

The Pentagon said Monday's strike targeting Godane was launched by U.S. special operations forces using manned and unmanned aircraft. The attack with Hellfire missiles and laser guided-munitions destroyed a vehicle and an encampment south of the Somali capital of Mogadishu, Pentagon spokesman Rear Adm. John Kirby said Tuesday.

"We are still assessing the results of the operation, and we'll provide additional information when and if appropriate," Kirby told reporters.

He added: "We certainly believe that we hit what we were aiming at," though he later said that was not meant to imply U.S. officials believed Godane was dead.