A gunman today killed an American missionary at the clinic where she worked as a nurse, in what was described as the first targeted killing of a U.S. citizen in Lebanon in more than a decade.

Bonnie Penner, 31, was slain by three shots to the head at the Unity Center, which houses a Christian chapel and a clinic.

There was no immediate claim of responsibility, but aid workers said the center had received warnings from anti-American Lebanese Muslim groups demanding it leave Lebanon.

Penner's British husband, Gary, said he forgave her killers and was convinced she would have done so, too. "God led us to Lebanon and we knew that we might die," he told the London Times. "I forgive anyone who did that."

It was the first such killing in Lebanon since the 1975-90 civil war.

Lebanese Prime Minister Rafiq Hariri condemned Penner's killing, saying it aimed to harm Lebanon's "efforts to strengthen stability and confidence in the country."

A colleague of Penner said the clinic had received threats in recent months.

"About three to four months ago the frequency of the warnings increased and the language toughened. They came from Lebanese Sunni Muslim extremists asking them to stop their activities and leave," the worker said.

He did not name the groups but said the warnings were conveyed to the center by Sunni Muslim clerics in Sidon.

Muslim clerics had accused the evangelical group of trying to convert Muslims.