A school that has educated children of Christian missionaries for nearly half a century has closed for the next year after an attack on the campus by Islamic extremists that killed six people, the director said Saturday.

"Given the trauma to the children and the possibility of further attacks, we cannot run a school that offers social and emotional support for children at this time," Russell Morton said in a telephone interview from the Murree Christian School, about 40 miles northeast of the capital, Islamabad.

Authorities say the three armed men who burst through the gates of the school on Aug. 5 belonged to the same group of Islamic extremists that four days later attacked a Christian hospital, killing three nurses with grenades. A fourth nurse later died of injuries.

Extremists are believed to be targeting Christians and Westerners in Pakistan in retaliation for the Musharraf government's support of the U.S.-led war on terrorism.

The school attackers allegedly blew themselves up with grenades the day after their assault, and at least one of the militants who attacked the hospital died on the scene. Police say they have arrested numerous members of a band of 15 to 20 extremists that executed the attacks. At least seven other alleged militants were have also been arrested in Lahore.

Still, there are fears that a new wave of terrorism has begun in Pakistan and many Western governments have urged their nationals to leave the country.

None of the Murree Christian School's 150 students, who hail from 20 countries, was injured in the attack earlier this month. The school board decided that closing the school was the only way to ensure their safety in the future, Morton said.

"It's desperately sad for the children who have become extraordinarily attached to the school," he said. "They're children who have a lot of change in their lives. For them, the school represents something unchangeable."

The board will decide by May whether to reopen for the next school year. The school year begins in early August and concludes at the end of June, with a long winter break.

The school's small campus, dominated by an imposing stone and stain-glassed church building, is perched on a hillside in Murree, a picturesque resort town founded by the British in 1851 to give colonial administrators a refuge from the sweltering, disease-ridden lowlands during the summer.

On Saturday, the school was abandoned except for a few remaining staff members trying to make travel arrangements home, Morton said. School officials, who leased the property from the Church of Pakistan, have hired security guards to watch the three-acre site while it sits idle.

The missionaries who board their children at the school while they work in Pakistan are making other arrangements, including home schooling, Morton said.

The school shut down soon after the Sept. 11 terror attacks in the United States, but reopened in February when officials decided it was safe to return to Pakistan. Now, once again, they believe leaving is their wisest option.