KABUL, Afghanistan (AP) – Three insurgents attacked a NATO base on the outskirts of Afghanistan's capital Saturday but were killed by coalition forces before they could enter the compound, NATO and Afghan police said.

The attack came just hours after Afghans angry over the burning of a Quran at a U.S. church stormed a U.N. compound in northern Afghanistan, killing seven foreigners.

NATO told The Associated Press in an email that three of its soldiers were wounded in Saturday's attack against Camp Phoenix, but that their injuries were not serious. The coalition said at least one attacker was possibly wearing a suicide vest. It added that the attack had ended.

Kabul provincial Police chief Gen. Mohammad Ayub Salangi said there were reports of three attackers involved and that two of them died when their vests detonated. He said a third was shot.

The base's gate had scorch marks on it, and an AP reporter at the scene saw some of the remains of at least one body belonging to a man who had blown himself up dangling from the gate.

Police officer Mohammad Shakir told the AP outside the base that two suicide bombers were involved in the attack and were apparently wearing burqas, the all-encompassing turquoise colored coverings worn by many women in Afghanistan. The body of a third insurgent was just inside the gate, he said. He was shot and killed, Shakir said.

Camp Phoenix is a base on the eastern edge of Kabul used mostly by American forces to help train the Afghan army and police.

On Friday, Afghans angry over the burning of a Quran at a small Florida church stormed a U.N. compound in northern Afghanistan, killing seven foreigners, including four Nepalese guards.

Afghan authorities suspect insurgents melded into the mob. They announced the arrest of more than 20 people, including a militant they suspect was the ringleader of Friday's assault in Mazar-i-Sharif, the provincial capital of Balkh province. The suspect was an insurgent from Kapisa province, a hotbed of militancy about 250 miles (400 kilometers) southeast of the city, said Rawof Taj, deputy provincial police chief.

The topic of Quran burning stirred outrage among millions of Muslims and others worldwide after the Rev. Terry Jones' small church, Dove Outreach Center, threatened to destroy a copy of the holy book last year. The pastor backed down, but the church in Gainesville, Florida, went through with the burning last month.

Four protesters also died in the violence in Mazar-i-Sharif, which is on a list of the first seven areas of the country where Afghan security forces are slated to take over from the U.S.-led coalition starting in July. Other demonstrations, which were peaceful, were held in Kabul and Herat in western Afghanistan, fueling resentment against the West at a critical moment in the Afghan war.

Protesters burned a U.S. flag at a sports stadium in Herat and chanted ``Death to the U.S.'' and ``They broke the heart of Islam.'' About 100 people gathered at a traffic circle near the U.S. Embassy in Kabul. One protester carried a sign that read: ``We want these bloody bastard Americans with all their forces to leave Afghanistan.''

U.N. peacekeeping chief Alain LeRoy said the top U.N. envoy in Afghanistan, Staffan De Mistura, who is in Mazar-i-Sharif, believes ``the U.N. was not the target.''

``They wanted to find an international target and the U.N. was the one there in Mazar-i-Sharif,'' LeRoy told reporters at U.N. headquarters in New York.

The U.N. and national governments said the dead included four security guards from Nepal; Joakim Dungel, a 33-year-old Swede who worked at the U.N. office; Lt. Col. Siri Skare, a 53-year-old female pilot working for the U.N.; and a Romanian citizen.

The Russian Foreign Ministry said the head of the mission in Mazar-i-Sharif, a Russian citizen, was injured in the attack, but not seriously.

Police who went to investigate said the U.N. compound was littered with broken glass and bullet casings.

Abdul Karim, a police officer in the city, said he saw the bullet-riddled bodies of three Nepalese guards lying in the yard and a fourth on the first floor.

He said another victim with a serious head wound died on a stairway to the basement of the compound. A man who was killed inside a room had severe wounds to his face and body, Karim said.

Munir Ahmad Farhad, a spokesman in Balkh province, said the protest began peacefully when several hundred demonstrators gathered outside the U.N. mission's compound, choosing an obvious symbol of the international community's involvement in Afghanistan to denounce the Quran's desecration. It turned violent when some protesters seized the guards' weapons and started shooting, then the crowds stormed the building and set fires that sent plumes of black smoke into the air, he said.

One protester, Ahmad Gul, a 32-year-old teacher in the city, gave a different account. He said the protesters disarmed three guards to prevent any violence from breaking out. Associated Press video showed protesters banging AK-47 rifles on the curb, breaking them into pieces. He said the protesters were killed and wounded by Afghan security forces.

``I disarmed three guards myself and we took out the bullets,'' Gul said, sternly shaking his finger as he shouted. ``With my eyes, I saw them (Afghan security forces) kill two and wound 10.'' As he talked, he became increasingly indignant and he started shouting: ``Death to America!'' ``We are going to fight.''

LeRoy, the U.N. peacekeeping chief, said the security guards, all Gurkhas, ``tried their best'' but were unable to prevent the large number of demonstrators, some armed, from storming the U.N. compound.

The U.N. Security Council held an emergency meeting late Friday and condemned the attack ``in the strongest terms.''

The U.N.'s most powerful body also condemned ``all incitement to and acts of violence'' and called on the Afghan government to bring those responsible to justice and take steps to protect U.N. personnel and premises.

Secretary-General Ban Ki-moon, who is in Nairobi, said it was ``an outrageous and cowardly attack against U.N. staff, which cannot be justified under any circumstances and I condemn in the strongest possible terms.''

He instructed De Mistura to assess the situation and take any ``necessary measures to ensure the safety of all U.N. staff.''

LeRoy said U.N. officials would be reviewing security for U.N. personnel in Afghanistan.

President Barack Obama condemned the attack and underscored the importance of the U.N.'s work in Afghanistan.

``We stress the importance of calm and urge all parties to reject violence and resolve differences through dialogue,'' Obama said.

At the U.S. State Department, spokesman Mark Toner said the burning of a Quran in Florida was contrary to Americans' respect for Islam and religious tolerance. ``This is an isolated act done by a small group of people and ... does not reflect the respect the people of the United States have toward Islam,'' he said.

The church's website stated that after a five-hour trial on March 20, the Quran ``was found guilty and a copy was burned inside the building.'' A picture on the website shows a book in flames in a small portable fire pit. The church on Friday confirmed that the Quran had been burned.

In a statement, Jones did not comment on whether the church's act had led to the deaths. Instead he said it was time to ``hold Islam accountable'' and called on the United States and the U.N. to hold ``these countries and people accountable for what they have done as well as for any excuses they may use to promote their terrorist activities.''

The U.N. has been the target of previous attacks.

In October 2010, a suicide car bomber and three armed militants wearing explosives vests and dressed as women attacked a U.N. compound in Herat in western Afghanistan. Afghan security forces killed the attackers and no U.N. employees were harmed. In October 2009, Taliban militants attacked a guesthouse used by United Nations workers in central Kabul. Eight people were killed, including five foreigners working for the U.N.