MOGADISHU, Somalia – Islamic militants from the Al-Qaida-linked al-Shabab group attacked a remote African Union base in Somalia on Friday, causing many casualties, the AU mission and a local official said.

In a tweet, the African Union mission confirmed there had been an early morning attack on their outpost in the village Lego, but did not provide any further details.

Mohammed Haji, an official in the Lower Shabelle region told The Associated Press by telephone that militants killed some 25 combatants, but there was no way to verify his claim.

He said they attacked the base entrance with a suicide car bomb before gunmen began their assault.

“They managed to infiltrate the entrance after the blast,” he said. “It was a complex attack.”

The governor of Lower Shabelle, Abdiqadir Mohamed Siidi, said that a minister for the regional South-Western State and the commissioner of Lego were now missing.

“During the attack they also beheaded women and they are still in control of large parts of the area,” he told the AP. He declined to give more details about the casualties.

Residents in Lego said that armed al-Shabab fighters are still patrolling parts of the village.

“The situation is still tense. Al-Shabab are back in control of Lego and arrested several people.” said Mohamed Aden, a local elder by phone from Lego, with gunfire echoing in the background.

Al-Shabab, which vowed it would step up attacks during the Muslim holy month of Ramadan, claimed responsibility for the attack.

The group’s spokesman Sheikh Ali Mohamud Rage said through its radio Andulus that the militants have taken control of the base which is on a key supply route for the AU forces.

The militants have been pushed out of much of the territory they once controlled across the Horn of Africa nation, including Mogadishu. But they remain a lethal threat, carrying out guerrilla attacks on government and civilian targets.

The U.N. special representative for Somalia, Nicholas Kay and African Union special envoy Maman Sidikou both condemned the attack.

Sidikou said in another statement that the AU mission would continue its joint operation with the army.

“This attack will not dampen our resolve to continue to support the Somali Government and people until they are free from terrorism,” he said.