At least 20 Afghan policemen were killed early Sunday when Taliban fighters stormed multiple security outposts in the volatile southern province of Zabul, officials said.

Local officials made desperate calls to Afghan television stations to seek attention as they were unable to get hold of senior authorities for help, highlighting the disarray in security ranks.

“This morning, a group of Taliban fighters armed with heavy and light weapons launched coordinated attacks on several police checkpoints in Shah Joy district of Zabul province, killing 20 policemen,” provincial governor Bismillah Afghanmal told AFP.

A district official told AFP that at least 15 others were wounded in the fighting.

The Taliban claimed responsibility for the attack on their website. The raid, the latest in a series of brazen Taliban assaults, underscores the insurgents’ growing strength more than 15 years since they were ousted from power by the US invasion of 2001.

Taliban militants launched their annual “spring offensive” in late April, heralding a surge in fighting as the US tries to craft a new Afghan strategy and NATO considers sending more troops to break the stalemate against the resurgent militants.

The offensive normally marks the start of the fighting season, though this winter the Taliban continued to battle government forces.

Taliban fighters dressed in army uniforms and armed with suicide vests attacked a military base outside the northern city of Mazar-i-Sharif last month, killing at least 135 policemen and soldiers.

Also Sunday, an interior ministry spokesman said that a German aid worker and an Afghan guard were killed and a Finnish national was abducted from a house in Kabul.

The three were working for a Swedish aid group called Operation Mercy, spokesman Najib Danish said.

An investigation was being conducted into the incident, which occurred at around 11.30 p.m. Saturday, he said but gave no further details.

Kidnapping is a longstanding problem in Afghanistan, mainly affecting Afghans abducted for ransom. However foreigners have also regularly been targeted, either for ransom or to put pressure on their governments.