The death toll in Wednesday's attack rose to seven and the seriously wounded Mayor Abdirahman Omar Osman was in a coma on Thursday. He and other officials were expected to be airlifted to Qatar for treatment, said Mohamed Ahmed, a government official at the Mogadishu hospital treating the mayor.

The new U.N. envoy, James Swan, was the bomber's intended target, Abdiaziz Abu Musab, al-Shabab's military spokesman, told local media.

Capt. Mohamed Hussein, a senior police officer, said the female bomber walked into a security meeting and blew herself up a few yards away from the mayor. It was just the fourth time the al-Qaida-linked al-Shabab had been known to use a female bomber in a suicide attack.

Swan had paid the Somali capital's mayor a brief visit and left the compound less than an hour before the bombing, an official at the mayor's office told The Associated Press.

In a statement, Swan condemned "this heinous attack which not only demonstrates a violent disregard for the sanctity of human life, but also targets Somalis working to improve the lives of their fellow Somalis." U.N. Secretary-General Antonio Guterres also condemned the attack.

It was not clear how the bomber managed to enter the mayor's office as visitors are required to pass through at least four metal detectors. Some security officials said the attacker might have coordinated with corrupt officials, offering them bribes for access.

Al-Shabab often targets government buildings such as the presidential palace and other high-profile parts of Mogadishu with bombings. The Somalia-based group was chased out of Mogadishu years ago but still controls parts of the Horn of Africa nation's south and central regions and is a frequent target of U.S. airstrikes.

The security officials said Wednesday's attack appeared to be a shift in tactics, as the extremists in the past had rarely managed to infiltrate heavily fortified government buildings without first detonating one or more vehicle bombs.

END/AP/UNB/KC