(Updates with militants firing at IEC building)
By Mirwais Harooni and Jessica Donati
KABUL, March 29 (Reuters) - Taliban insurgents attacked the Independent Election Commission headquarters in the Afghan capital of Kabul on Saturday, staff and police said, the latest in a spate of attacks ahead of next week's presidential election.
"Four suicide bombers armed with light and heavy weapons have entered a building near the IEC headquarters and are shooting towards the IEC compound and at passers by," Mohammad Zahir, the Kabul police chief, told reporters near the site of the attack.
The IEC compound is also close to offices used by the United Nations Office Complex in Afghanistan (UNOCA) and other international organisations.
"I am here ... the attack is going on around the IEC compound," IEC spokesman Noor Mohammad Noor told Reuters by telephone from a safe room inside the building.
Staff heard an initial explosion at around midday, and that was then followed by gunfire.
The Taliban claimed responsibility for the attack, the second launched against an IEC office in the capital this week as the Islamist insurgency seeks to derail the April 5 election it calls a Western-backed "sham".
IEC spokesman Noor said that IEC personnel were safe and that Afghan security forces were in control of their building.
U.N. staff at the complex near the IEC were instructed to take refuge in saferooms until further notice.
The attack was the second to strike Kabul in less than 24 hours, after Taliban insurgents targeted a guesthouse used by a U.S.-based aid group.
An Afghan child was killed by the initial blast and Afghan security forces battled with the militants for hours before clearing the compound building. The aid workers were not hurt.
With a week to go before Afghanistan's presidential election, escalating violence across the country risks undermining the credibility of a vote meant to mark the first democratic transfer of power in Afghan history.
Violence has escalated in Afghanistan in recent weeks with almost daily explosions and gunfights around the country.
Taliban suicide bombers and gunmen attacked an election commission office in Kabul on Tuesday, and last week, nine people including an AFP journalist and an election observer, were killed in an attack on a highly fortified hotel in the capital.
Afghanistan is holding an election to choose a successor to President Hamid Karzai, who is constitutionally barred from running for another term in office.
It will be seen as a major test by foreign donors who are hesitant about bankrolling the government after the bulk of NATO troops stationed in Afghanistan withdraw later this year. (Reporting by Jessica Donati and Mirwais Harooni; Editing by Jeremy Laurence)