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KABUL, Afghanistan - A rogue cop shot and killed at least three Americans, including a pediatrician, at a children's hospital in the Afghan capital on Thursday — the second time this month a member of the Afghan security forces has turned a gun on foreign civilians.

The U.S. Embassy in Kabul confirmed that three Americans were killed in the attack at the CURE International Hospital, which is in a walled compound next to the American University of Afghanistan in western Kabul.

National Security Council spokeswoman Caitlin Hayden called the shooting "despicable and cowardly" in a statement issued by the White House.

"The United States continues to strongly support those in Afghanistan who abhor this violence and we are working to build a peaceful, prosperous future for themselves," the statement said.

With great sadness we confirm that three Americans were killed in the attack on CURE Hospital. No other information will be released at... -U.S. Embassy Kabul (@USEmbassyKabul) April 24, 2014

Citing colleagues, NBC Chicago reported that Dr. Jerry Umanos was one of the Americans who had been fatally shot. He had worked at the Lawndale Christian Health Center for 16 years.

Since 2011, he had been a volunteer for the non-profit Empowerment Health.

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"Jerry and I worked closely for years to develop and implement training programs that provide local Afghan women with basic health education and skills to provide critical health services and best practices in their communities," co-founder Evan Russell said.

"Jerry's daily impact on this program, and on so many other people, will be missed forever."

Chicago-area pediatrician Dr. Jerry Umanos was killed in an attack in Kabul, Afghanistan, on Thursday. Lawndale.org

Afghan Health Minister Soraya Daril said two of the dead were father and son. They were believed to be visiting Umanos. Earlier, district police chief Colonel Hafiz Alizada said an American woman was shot and wounded.

According to Alizada, the gunman later shot himself in the head and was in critical condition. Pennsylvania-based charity CURE said workers there treated the shooter before he was taken into custody.

CURE, which specializes in children's and maternal medicine, treats 37,000 patients annually at the facility.

"CURE International remains committed to serve the people of Afghanistan. Please join us in praying for the families of the victims," a spokesman said.

There was no immediate claim of responsibility for Thursday's attack.

Afghanistan – which voted April 5 in presidential elections - has seen a spike in violence against government institutions and foreign organizations in recent weeks.

The Taliban have ramped up attacks ahead of the withdrawal of NATO.

Earlier this month, an Afghan police officer shot and killed Associated Press photographer Anja Niedringhaus and wounded correspondent Kathy Gannon.

In March, Taliban gunmen opened fire inside a fortified luxury hotel frequented by foreign nationals in Kabul, killing a prominent Afghan journalist and eight other people.

A Swedish journalist was gunned down in broad daylight on a Kabul street and Taliban insurgents attacked a compound housing U.S.-based aid organization Roots for Peace.

The Taliban were also behind a January attack on a popular Lebanese restaurant in the capital which left 21 dead, including 13 foreigners.

The spate of violence comes as NATO forces prepare to withdraw at the end of 2014 and has prompted many expatriates and international organizations to rethink their presence in Afghanistan.

F. Brinley Bruton and Jamieson Lesko of NBC News contributed to this report. Cassandra Vinograd reported from London.