Jerry Umanos was at work by 9 a.m. Thursday, ready for another day in the struggle to treat sick children in dirt-poor Afghanistan. The Chicago resident had spent nearly a decade at a Christian hospital in Kabul, and he loved his work, his colleagues said.

But as the doctor greeted two American visitors outside the building, an Afghan police officer walked up. Without saying a word, he opened fire, leaving all three dead, officials said.

The killings were the latest in a string of deadly assaults on foreign civilians in Afghanistan, who are increasingly being targeted by Taliban militants and renegade Afghan security officials.

In the past three months, more than 20 foreign civilians have been slain in attacks at a restaurant, an upscale hotel and other venues where expatriates congregate. The dead have included election observers, journalists and aid workers.

Javid Kohestani, a retired Afghan army general and Kabul-based security analyst, said Taliban fighters and their sympathizers appear to be stepping up attacks on civilians as military targets become more difficult to find with the U.S.-led international coalition continuing to pull out troops.

The Taliban wants “to frighten foreigners and disrupt their reconstruction and development work,” Kohestani said.

The violence comes as Afghanistan is in the midst of choosing a new president, with preliminary results from the first round of balloting due within days. In the past, violence has flared during presidential campaigns and elections. But it was usually directed at the military or the security forces.

Umanos had been working for Cure International Hospital in Kabul, which is part of a network of clinics operated by a Pennsylvania-based charity. The organization’s mission is to help impoverished countries by delivering “life-changing medical care and the good news of God’s love to children and families with treatable conditions,” according to the group’s Web site.

The attack occurred as doctors and nurses were arriving for work. The identities of the other two Americans who were killed have not been released.

But Afghan officials said they were a father and a son who were medical professionals and were on a visit. The U.S. Embassy in Kabul declined to identify the men but issued a statement saying the three Americans were “humanitarians . . . dedicated to improving the lives of Afghans by providing a full range of medical services including reconstructive surgery to children with physical disabilities and pre- and post-
natal care for mothers.”

An American nurse was wounded in the attack, according to Afghan Health Minister Soraya Dalil.

Afghan security officials said the gunman, who had been assigned to help protect the hospital, turned his weapon on himself after shooting the Americans. He survived and was taken inside the hospital to be treated. He was later released and arrested by Afghan security officials.

“We are still trying to determine the cause of this attack,” said Abdul Zahir, Kabul’s police chief.

In a statement, the White House condemned the shooting, calling it “despicable and cowardly.”

‘He knew the dangers’

Umanos was aware of the risk of violence in Afghanistan. He had gone to a popular Lebanese restaurant in Kabul multiple times before it was attacked by Taliban insurgents in January. And a dentist who lived near him had been killed a few years earlier.

“He knew the dangers,” said Art Jones, the founding chief executive of Lawndale Christian Health Center, an inner-city Chicago institution that Umanos had been affiliated with for 25 years. “But he was really drawn to serving those kids.”

Umanos, a pediatrician, had his introduction to Afghanistan when he visited a couple he knew from the clinic who had gone there to help people with tuberculosis.

Umanos decided that one could eventually find people to go work in impoverished areas of Chicago, “but there weren’t a lot of people willing to come work in Afghanistan,” Jones recalled.

So Umanos began spending the majority of the year in Afghanistan, coming back for a month or two to work at Lawndale and spend time with his family before returning, Jones said.

In a televised news conference, Lawndale doctors and administrators said they were grief-

“This loss is a great loss for his family, for those of us he worked with as well as for the people of Afghanistan,” said Bruce Rowell, the medical director of clinical quality at the center.

In addition to his work with Cure, Umanos had been the community health coordinator for Empowerment Health, a nonprofit group dedicated to improving the health of Afghan women and children.

Umanos had worked for years to develop training programs to give Afghan women better health education and skills, according to Evan A. Russell, co-founder of the group.

“Our efforts in the community will continue on, and we remain deeply committed to the mission to which he devoted his life, but Jerry’s daily impact on this program, and on so many other people, will be missed forever,” Russell said in an e-mail to The Washington Post.

Foreign civilians vulnerable

The attack occurred as foreigners living and working in Afghanistan were already rattled by the wave of brazen violence.

The Taliban has asserted responsibility for much of the violence, including a March 20 assault on the Serena Hotel in Kabul that killed nine civilians, among them two Canadians and an American-Bangladeshi dual national. But some of the attacks have been carried out by Afghan security officials.

For years, the U.S.-led military coalition has struggled to combat “green-on-blue” attacks in which Afghan soldiers have turned their weapons on NATO coalition troops who were training or supervising them.

Increasingly, civilians also are vulnerable to such attacks.

About three weeks ago, an Afghan police officer shouted “Allahu Akbar” (God is great) before shooting an Associated Press photographer and reporter who were sitting in a vehicle in Khost province in eastern Afghanistan. The photographer, Anja Niedringhaus, a German citizen, was killed. The reporter, Kathy Gannon, a Canadian, was seriously wounded.

That attack occurred one month after Swedish journalist Nils Horner was fatally shot in a midday attack in Kabul.

Cure International was founded in 1996 by Scott Harrison and his wife, Sally, to help children with disabilities.

The Cure hospital in Kabul opened in 2005 and has 27 doctors and 64 nurses, according to the group. It treats 37,000 patients annually.

Thursday’s shooting marks the second time in less than a month that a Christian charity has come under attack in this overwhelmingly Muslim country.

In late March, the Taliban assaulted a heavily guarded guesthouse in Kabul for employees of Roots of Peace, a San Francisco-based organization that focuses on agricultural projects. The hours-long standoff ended after Afghan forces intervened.

That guesthouse was next to a Christian charity and day-care center, which may have been the intended target.

Despite the violence, Cure International said Thursday that it will not abandon Afghans.

“Cure International remains committed to serving the Afghan people,” the organization said in a statement.

Berman reported from Washington. Sayed Salahuddin in Kabul and William Branigin in Washington contributed to this report.