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By Mirwais Harooni and Hamid Shalizi
KABUL, March 28 (Reuters) - Six foreigners including three Americans were trapped inside a Kabul guesthouse on Friday after a group of Taliban gunmen laid siege to the building, police said.
A Reuters witness at the scene saw about 20 people who appeared to be non-Afghans being evacuated from the guesthouse in an upmarket residential area of the capital, many looking frightened and in shock.
A gun battle erupted after a Taliban suicide bomber blew himself up outside the building and insurgents forced their way in, and heavy gunfire resonated in the area for more than an hour after the initial explosion.
Kabul is already on high alert and people are on edge ahead of next week's presidential election which the Taliban have vowed to disrupt.
"A suicide bomber detonated his car loaded with explosives in front of a guesthouse used by foreign and Afghan citizens and now a number of suicide bombers are apparently inside," said Hashmat Stanikzai, a spokesman for Kabul's police chief.
"A gunfight is under way. There are no reports of possible casualties," he said adding that Afghan forces were trying to enter the building to rescue those trapped inside.
Deputy interior minister, General Ayoub Salangi, told Reuters that at least one Australian citizen was among those rescued, but the nationalities of the others were not clear.
Kabul police chief Mohammad Zahir said three U.S. citizens, a Peruvian, a Malaysian and one unidentified African were still inside.
A senior police official said the target appeared to be a USAID-funded Afghan non-governmental organisation.
The Taliban immediately claimed responsibility, saying in a statement the target was a foreign guesthouse and a church.
Reuters television footage showed Afghan forces sealing off the street in the south of the capital and military convoys rushing to secure the area.
The nation of 30 million holds a presidential election on April 5 to elect a successor to outgoing President Hamid Karzai.
It will be a test for foreign donors hesitant about bankrolling the government after the bulk of NATO troops stationed in Afghanistan withdraw this year.
Violence has spiralled ahead of the vote, with Taliban suicide bombers and gunmen attacking an election commission office in Kabul on Tuesday.
Last week, nine people including an AFP journalist and an election observer were killed in a brazen attack on a highly fortified hotel in Kabul. (Writing by Maria Golovnina; Editing by Mike Collett-White)