Police say the siege of a Kabul guest house has ended after security forces killed the last remaining militant inside the building.
Interior Ministry spokesman Sediq Sediqi told RFE/RL that a child bystander was killed in the attack and a driver in a vehicle near the explosion was also killed.
Sediqi said all five of the attackers were killed and four guards were wounded. He said all the foreigners staying at the guest house were unharmed and had been taken to a safe place.
Ayub Salangi, a deputy interior minister, told RFE/RL corresondent Arif Ludin in Kabul that the building housed Roots for Peace, a USAID-funded nongovernmental organization.
Security forces quickly surrounded the structure and initiated an operation to neutralize the attackers.
The U.S. Embassy in Kabul said it condemned the "attack on an organization that only seeks to help Afghans improve their lives and livelihoods."
The embassy said on Twitter, "Roots of Peace has been a valued partner for Afghanistan, with the support of USAID."
The aid group has been working in Afghanistan since 2003, running projects to turn minefields into vineyards and orchards.
The Taliban issued a statement claiming responsibility for the attack, saying the militant group targeted the building because it was being used as a church to convert Afghans to Christianity.
Militants frequently plot attacks on high-profile targets, including hotels and restaurants frequented by Westerners.
Meanwhile, security officials say at least 10 people were injured in a stampede at a campaign rally in the northern Afghan city of Mazar-e Sharif.
According to officials, no one was killed in the incident.
However, witnesses told RFE/RL that three people were killed in the stampede, which occurred during a rally for presidential candidate Abdullah Abdullah.
Hundreds of people crowded the stage to shake Abdullah's hand, causing the stage to collapse.
Abdullah and his entourage escaped unharmed.
Abdullah, a former foreign minister, is a leading contender in Afghanistan's April 5 presidential election.
Security remains the biggest challenge for the election campaign as the Taliban militants have vowed to disrupt the vote.
Noor Muhammad Noor, a spokesman for Afghanistan's Independent Election Commission (IEC) says that some polling stations might not open on the election day due to security concerns.
A latest assessment of the situation indicates the number of the polling stations under increased security threats is considerably higher than the previous estimates, which stood at nearly 400, Noor told Radio Free Afghanistan.
Thomas Rymer, a spokesman for the Organization for Security and Cooperation in Europe's Office for Democratic Institutions and Human Rights (ODIHR), says "security is a clear concern" for everyone, including international monitors.
He said half of the 15-strong OHIDR monitoring team has left Afghanistan following last week's deadly attack on the Kabul hotel where the team was based.
"Security is clearly a concern, and we've looked into that situation very carefully with regard to our staff. That can never be 100 percent, of course, but we are satisfied, at present at least, that the conditions are good enough for them to work there," Rymer said.
Rymer said the remaining ODIHR staff in Afghanistan are "working more to provide expertise to the Afghanistan authorities in how to organize, how to run a democratic election."
"The OSCE participating states have asked our office - the Office for Democratic Institutions and Human Rights -- to provide support to the Afghanistan's authorities in the running the administration, the organization of elections in line with international standards for democratic elections," Rymer said.
Altogether 11 candidates were registered to run in the election, but three have withdrawn from the race.
The constitution bars incumbent Hamid Karzai from seeking a third term.