Islamist fighters attacked a government facility in the capital of Somalia on Sunday, detonating a bomb before storming the structure and killing at least five people, according to the ministry of information.

Around noon, al Shabaab attackers stormed the building housing the mayor of Mogadishu’s office and engaged security troops in gunfire, according to the ministry and eyewitnesses.

According to the ministry’s Facebook page, security killed six of the extremists and cleared the area by around six o’clock.

Al Shabaab has stepped up attacks in a show of resilience since President Hassan Sheikh Mohamud’s government launched an offensive against the al Qaeda-linked group in August.

“We were in the office and we were deafened by a blast. We ran out. Gunfire followed,” Farah Abdullahi, who works in the mayor’s office, told Reuters.

Sixteen people were injured in the attack, Abdikadir Abdirahman, director of Aamin Ambulance Services, said.

The mayor’s office is in the local government headquarters building in a well-guarded area of Mogadishu.

Roads in the area have concrete barriers and multiple roadblocks. The building is about 1.5 km (1 mile) away from Villa Somalia, the president’s office.

Al Shabaab said in a statement its suicide bombers struck, “then foot fighters entered the building after killing the building guards”.

Al Shabaab, which has been fighting the government since 2006 and seeking to impose its own interpretation of Islamic law, frequently carries out bombings and gun attacks across the country.

State TV in Jubbaland, one of the country’s semi-autonomous states, reported on Sunday that regional and Somalia federal forces had launched attacks on al Shabaab and taken control of Janay Abdale town from the militants. This was a sign that the government was extending its offensive against the group into the country’s south.