A suicide bomber detonated his explosives-laden car outside a police station in the country's south on Sunday, killing 11 police officers and wounding 15, the interior ministry said.
Police officials said the attack took place in Mukalla, the capital of the southern province of Hadramawt. The bomber, believed to be an al-Qaida militant, drove his car very close to the station and argued with officers to draw in more victims before detonating the explosives, they said.
The blast collapsed part of the building while police officers were having lunch inside, killing the civilian cook, they added.
A senior police officer said the attack was believed to be a swift retaliation for the big losses sustained by al-Qaida militants over the past two weeks, after government forces struck them in the southern region of Mahfad and recaptured a sprawling al-Qaida base between Shabwa and Abyan provinces.
He said the militants left big depots of weapons in the base, including explosives and materials for rigging cars to be used by suicide bombers. The army also found computers and communications equipment inside the mountains caves.
He said the militants fled to the mountains and that at least 12 cars carrying them were seen heading to the northwest province of al-Jawf as the army sets up military posts and checkpoints in recaptured parts of Mahfad, Azzan and Meyfaa.
The officials spoke on condition of anonymity because they are not authorized to brief journalists.
Washington considers Yemen's al-Qaida in the Arabian Peninsula the most active branch of the group in the world, and has assisted the government with logistics, training and drone attacks. The militants have fought back, targeting government buildings and security forces.
Meanwhile Sunday in the capital, Sanaa, security forces clashed with suspected al-Qaida gunmen in an area not far from the presidential palace, killing three militants.