Islamabad, Pakistan ? A grenade attack on a Protestant church packed with Sunday worshippers killed five people including an American woman and her daughter in an assault clearly aimed at Pakistan’s foreign community.

No group claimed responsibility for the attack, in which at least one young man in black some witnesses said two ran through the center of the church hurling grenades. But suspicion fell on Islamic extremists.

Ten Americans were among the 45 people injured, most of whom were foreigners, police and hospitals said. One body remained unidentified late Sunday, and officials said it may be the assailant.

Britain’s Foreign Secretary Jack Straw said the assault was aimed at undermining Pakistan’s pro-U.S. president at a time when he is trying to quell Islamic fundamentalism following the Taliban’s fall in neighboring Afghanistan.

The attack occurred at 10:50 a.m. during a sermon before 60 to 70 worshippers. Dozens of police and soldiers rushed to the scene.

The church, about 400 yards from the U.S. Embassy, is located in the guarded diplomatic quarter in the heart of Pakistan’s capital and primarily serves the foreign community. The overwhelming majority of Pakistanis are Muslim and few Pakistani Christians live in Islamabad.

Survivors spoke of deafening blasts, choking smoke and pandemonium. They said terrified parents screamed for their children and stunned worshippers dived beneath chairs and behind cement pillars as bits of flesh were hurled through the air.

“There was blood, blood, blood, intestines lying on the floor,” said Elisabeth Mundhenk, 54, of Hamburg, Germany as she awaited treatment for shrapnel wounds at a hospital. “It was horrific. There was a horrible smell and we could barely breathe.”

The U.S. Embassy identified the dead Americans as Barbara Green and her daughter Kristen Wormsley, a senior at the American School in Islamabad.

Green and her husband, Milton Green, worked at the U.S. Embassy she in administration and he in the computer division. Milton Green and the couple’s young son were also injured but not seriously, according to police.

The other dead included one Afghan, one Pakistani and the one unidentified, Pakistani officials said.

Six or seven of the injured were in serious condition, District Judge Tariq Mehmood Khan said.