This has jeopardized the scheduled presidential election runoff Nov. 7.

The incident occurred amid rising U.S. troop casualties in Afghanistan, and could affect Washington’s decision to dispatch additional troops to the war-torn Central Asian country.

Three Taliban gunmen wearing police uniforms visited a U.N. guest house in the Afghan capital of Kabul around 5:30 a.m. yesterday. They were armed with suicide bombing vests, AK-47 automatic rifles, and hand grenades.

Their nationalities remained unknown, but an Afghan army captain told AFP, “All the terrorists were students from Pakistan who received suicide bombing training.”

In the firefight between the gunmen and police, the guest house was engulfed in flames and smoke. U.N. staff were seen rushing out and shouting, according to BBC News.

A resident who entered the building was quoted as saying, “It was obvious that the terrorists detonated bombs. It was horrendous to see cuts of flesh scattered around.”

The foreign-owned Serena luxury hotel in Kabul also came under rocket attack. A flurry of terrorist attacks big and small continued in the city throughout the day, with a rocket grenade exploding at a site near the presidential office.

With the Afghan capital in chaos, police immediately put barricades to block traffic at main locations on main streets.

The Taliban attacked the United Nations 10 days ahead of the final round of the presidential election apparently to raise fears among residents and block them from voting, Reuters said. Around 2,000 U.N. staff are stationed in Kabul primarily to support the election.

Refusing to recognize the authority of the incumbent government, the Taliban has opposed the election itself. It issued a warning Sunday that it will attack anyone helping or participating in the vote.

In the first round of the presidential election Aug. 20, the Taliban committed a string of attacks at many locations to block the vote, killing dozens.

Amid the chaotic situation, presidential candidates have intensified their war of nerves. Former Foreign Minister Abdullah Abdullah, who ranked second in the first round, demanded a new chairman of the election commission to ensure a clean election.

But incumbent President Hamid Karzai immediately rejected the demand.

Certain analysts say Abdullah could boycott the election’s final round. AFP said that even after the decision was made to hold a second round, Abdullah is not staging an election campaign.

The latest fighting and attacks have added to the agony of U.S. President Barack Obama, who is debating whether to dispatch additional troops to Afghanistan.

A collision between U.S. Army choppers in Afghanistan killed 11 American soldiers Sunday and a Taliban attack killed eight more Monday, bringing the U.S. death toll to 53 this month.

The Associated Press said that under the circumstances, the attack on the guest house in Kabul has raised confusion in Afghanistan, and Washington will likely see mounting controversy over whether “it is worth risking additional casualties there.”