Washington also asked Yemeni authorities to provide more protection for Americans after a doctor and two other medical workers were shot and killed at Jibla Baptist hospital, 105 miles (170 km) south of the capital Sanaa.

Yemeni officials said the gunman belonged to the Islamic opposition Islah Party.

"We strongly condemn and deplore the murder of three American citizens who were providing humanitarian assistance to the Yemeni people," said White House spokesman Scott McClellan. "Our intention is to bring to justice any and all people who were responsible for these murders."

US President George W Bush, who is spending the New Year holiday at his ranch in Crawford, Texas, was notified of the attack by his staff early on Monday morning.

The State Department called the shootings "despicable" and said it would consider adjusting a Nov. 30 warning advising Americans to defer nonessential travel to Yemen.

"We're working with them as well to see what other steps might be taken, anything else they can do to provide security immediately for Americans who are in locations such as this, working at a hospital," said spokesman Philip Reeker.

ONE SUSPECT IN CUSTODY

Police arrested Abed Abdel Razzak Kamel, 30, for the slayings. Officials in Yemen said he had entered the hospital posing as a patient and that he thought the killings would bring him closer to God.

"Yemeni officials have one individual in custody and we will work with them to bring to justice all of those responsible," McClellan said.

US officials said it was too early to jump to conclusions about whether the man acted alone or had any link with groups such as al-Qaeda. McClellan declined to label the murders a terrorist attack, but said the United States was working closely with Yemeni officials on the case.

There are about 30,000 Americans in Yemen, the vast majority of whom are US citizens of Yemeni origin. Many have double nationality and they are unlikely to be targets of militant Islamists opposed to US policy.

The State Department has advised Americans to put off nonessential travel to Yemen because of the militant presence there. The US Embassy does not allow the children of embassy staff to live in the country.

"We need to let the investigation continue," said McClellan said. "This underscores the dangerous world we're living in these days ... We take this very seriously."

MISSIONARIES TO GO ON WORKING

The Christian missionary group to which the victims belonged said it planned to go on working in the hospital in Yemen where it has operated for 35 years.

"We would not choose to end our ministry and service because of risk and danger to our personnel," said Jerry Rankin, president of the Southern Baptist International Mission Board. "We anticipate the hospital continuing. Our people are committing to continue ministering there," he told reporters at the board's Richmond, Virginia, headquarters.

Those killed were identified as Martha Myers, 57, a physician from Montgomery, Alabama; William Koehn, 60, of Arlington, Texas, a hospital administrator; and Kathleen Gariety, 53, of Wauwatosa, Wisconsin, a purchasing agent. Donald Caswell, 49, a pharmacist from Levelland, Texas, was recovering after an operation to remove two bullets.

Rankin said the gunman smuggled a rifle into the hospital under his coat, cradling it as if it were a baby. The Americans were meeting at the start of the hospital's work day when the gunman burst into the room and killed the three.

"The gunman reportedly then moved to another room where he wounded Caswell," Rankin said. "He also aimed his gun at a Filipino hospital employee, but the weapon did not fire."

More than 40,000 patients a year are treated at the facility, which provides free care and medicine to the needy. It also has responded to relief needs during earthquakes and famine.

(China Daily December 31, 2002)