Insurgents killed five people in two separate attacks in Afghanistan on Wednesday. In the western Badghis province, militants attacked a checkpoint, killing two police and wounding four others, said Abdul Aziz Beg, the head of the provincial council. Another four police were missing after the attack early Wednesday. It was not clear who was behind the attack. In the central Ghor province, the Taliban killed three people, including a tribal leader, in an attack on a district police headquarters. Police spokesman Iqbal Nezami said security forces repelled the attack late Tuesday. The Taliban have stepped up attacks across the country since announcing their annual spring offensive last month. On Tuesday, at least 16 people were killed and 38 wounded when a minivan packed with explosives exploded as members of the security forces were trying to defuse it in southern Afghanistan, officials said. Police and intelligence officers in the city of Kandahar had already cleared the area around a bus station where the van was found, said the provincial governors spokesman Daud Ahmadi. "As the security forces were trying to defuse the van, it detonated," said police spokesman Mohammad Qasim Azad. "The latest figures show 16 dead and 38 wounded people brought to the hospital. We still have two ambulances at the site because there might be more people under the rubble," said Dr. Nehmat Barak, chief of the Mirwais Hospital in Kandahar. Ahmadi confirmed the toll, adding that the dead included four members of the security forces. At least five children and 10 members of the security forces were among the wounded. No group immediately claimed responsibility. The blast was quickly condemned by President Ashraf Ghani, who praised the "brave" officers who dealt with it. A US government watchdog also warned Monday that upbeat assessments of improving security in the country did not match facts on the ground. The Pentagons Office of the Inspector General said there were "few signs of progress" in the fight against the Taliban. Top US officials and military commanders insist that Afghan police and troops -- who have suffered thousands of casualties and are beset by low morale and corruption -- are now doing a better job. But the Taliban still control swathes of the country and are staging repeated attacks, while the ISIS group has conducted a series of high-profile suicide blasts in Kabul and elsewhere.