Kabul: The political office of the Afghan president's running mate was hit by a large explosion and stormed by several gunmen who remained holed up inside, Afghan officials said Sunday.

The attack in the capital, Kabul, killed at least two people and came on the first day of campaigning for presidential elections, scheduled for late September. Vice-presidential candidate and former intelligence chief Amrullah Saleh was "evacuated from the building and moved to a safe location," said Nasrat Rahimi, the interior ministry spokesman. He said that while the gunbattle was still ongoing, the first and second floors of the building had been cleared by security forces. He said two attackers were still inside and that one gunman had been killed in the shootout. President Ashraf Ghani also tweeted that Saleh was unharmed in the "complex attack" targeting the Green Trend party headquarters.