KANDAHAR, Afghanistan — Taliban fighters overran checkpoints in a nighttime raid in Afghanistan's volatile southern Helmand province, killing at least 20 police officers as the battle raged into Saturday, authorities said. The assault came as Afghanistan's military acknowledged the Taliban controls at least four districts across the country. The attacks in Helmand hit police checkpoints in the Musa Qala district, long a Taliban stronghold, said Mohammad Ismail Hotak, the head of the province's joint coordination of police and military operations. He said the attacks wounded at least 10 officers, though the Taliban also seemed to have suffered high casualties. Saqi Jan, the head of police logistics in Musa Qala, said area checkpoints were manned by officers from the neighboring district of Baghran who had been forced out by earlier Taliban attacks. “Baghran has been under Taliban control since last year, so these police came to Musa Qala and built themselves a small compound and some checkpoints,” he said. The Taliban claimed responsibility for the attacks. The militants have been targeting vulnerable police checkpoints across the country since launching their summer offensive in April. — AP