ISLAMABAD, PAKISTAN

Pakistan put its military and police on high alert Monday, tightening up security at Islamabad diplomatic missions and churches after a terrorist attack on a Protestant congregation killed five people, including two Americans.

In an assault clearly directed at foreigners, at least one man dressed in black hurled grenades into the Pakistan International Church on Sunday, sending shrapnel through the crowd and splattering the sanctuary's walls with blood and flesh.

The dead included a U.S. Embassy worker and her teen-age daughter. More than 45 people - most of them foreigners - were injured.

Ten Americans were among the 45 injured, along with 12 Pakistanis, five Iranians, one Iraqi, one Ethiopian and one German, police said. The injured also included Sri Lankans, Afghans, Swiss, Britons, Australians and Canadians.

Survivors of the attack at the Protestant International Church spoke of deafening blasts, choking smoke and pandemonium as terrified parents screamed for their children. Stunned worshippers dived beneath chairs and behind cement pillars as grenades exploded during the sermon. No group claimed responsibility.

President Bush condemned the attack in the guarded diplomatic quarter at the heart of Pakistan's capital, about 400 yards from the U.S. Embassy compound.

Assistant Secretary of State Christina Rocca cut short a visit to India and flew to Pakistan to accompany the bodies of the dead Americans - Barbara Green and her 17-year-old daughter Kristen Wormsley - back to the United States.

In a statement released in New Delhi, Rocca said the "cowardly murders" in Islamabad "are yet more evidence of the necessity to continue with the international coalition's war against terrorism."

The State Department warned Americans abroad of "the imminent threat of terrorist actions" and said terrorists "will seek softer targets" as security is increased at official U.S. facilities.

Musharraf called a meeting Monday with top military commanders to review Pakistan's overall security. A second high-level meeting was scheduled for Tuesday.

Witnesses gave conflicting reports on the number of attackers, ranging from one to three. Late Sunday, Durrani said authorities believed only one attacker was involved. One unidentified person who may have been the assailant, Pakistani officials said he could be attacker who died during the explosions.