"I can confirm an attack at the IEC (Independent Election Commission) headquarters," Noor Mohammad Noor, the IEC spokesman, told AFP.
"We heard two explosions inside the IEC compound, the sound of firing is still ongoing, but people are safe and are in (reinforced) safe rooms."
Interior ministry spokesman Sediq Sediqqi said: "Initial information shows that three or four attackers have occupied a building and are firing on the IEC office."
Yesterday, Taliban militants attacked a Kabul guesthouse used by a US anti-landmine charity, killing two people.
The Taliban have vowed a campaign of violence to disrupt the polls on April 5, urging their fighters to attack polling staff, voters and security forces in the run-up to election day.