Updated

An Afghan official says Taliban fighters stormed a police checkpoint overnight in southern Helmand province, killing four policemen.

Deputy district Governor Mohammad Rassoul says the attack happened in Sangin district and that the Taliban have captured the checkpoint.

Rasssoul says the government forces are trying to retake the post and that clashes are underway at the location between Afghan police and the Taliban.

The attack took place as U.S. Secretary of State John Kerry was in Kabul on Friday for talks aimed at preventing the fragile country from collapsing into political chaos after disputed elections.

Kerry, who arrived the day before, is to urge two contenders from the presidential election runoff to accept results of an ongoing audit of all ballots and form a national unity government by early September.