Taxila, Pakistan ? Assailants hurled grenades at worshippers leaving church Friday, killing three Pakistani women and reinforcing fears that Islamic militants are targeting Christians and Westerners in Pakistan in retaliation for the government’s support for the U.S.-led war on terrorism.

Investigators said they suspected the attackers were from the same cell of militants behind an assault Monday at a school for children of Christian missionaries in Murree, outside the capital.

Pakistani protesters, belonging to the Christian minority, chant slogans against attacks on Christian interests. Three Pakistani nurses were killed and more than 25 other Pakistanis were wounded Friday in an attack in Taxila. It was the second assault on a Christian institution in less than a week.

Pakistan has been rocked by terrorist attacks since President Pervez Musharraf abandoned his Afghan Taliban allies and joined the U.S.-led anti-terror campaign after Sept. 11.

“We have drawn the conclusion that a group of between 15 to 20 terrorists is actively trying to kill Christians and Westerners to express their anger against Pakistan’s support for the United States in the war against terrorism,” chief police inspector Raja Mumtaz Ahmad said.

He said the group was believed to have divided into four teams to stage attacks in northern Pakistan. He said security had been stepped up at Christian churches throughout the country. Christians make up less than 2 percent of Pakistan’s 145 million people, almost all the rest of whom are Muslim.

“It looks to be the same chain of terrorists,” said S.K. Tressler, the government minister in charge of minority affairs. “It is clear that terrorists are targeting the Christian community in Pakistan.”

In Friday’s attack, three men, one of them brandishing a pistol, ran through the front gate of a Presbyterian-supported hospital in Taxila, 25 miles west of Islamabad. They locked two watchmen in a guard booth and then hurled grenades at women leaving the church on the hospital grounds.

Three Pakistani nurses were killed, and at least 25 other people were wounded, half of them seriously. One attacker died when shrapnel from an exploding grenade entered his back and pierced his heart, police said. The others escaped.

The attack took place four days after several gunmen raided the Murree Christian School about 40 miles east of the capital, killing six Pakistanis including guards and non-teaching staff. None of the students, who come from 20 countries, was injured.

On the following day, three men blew themselves up to avoid arrest after police stopped them in Pakistani-controlled Kashmir, police said. Police said the three had boasted of taking part in the Murree raid and claimed other groups would soon carry out similar attacks against “Americans and nonbelievers.”

Regional police commander Moravet Shah said the attacker who was killed in Taxila was wearing Western athletic clothing similar to that worn by the school attackers.

Most attacks against Westerners or Western interests have been centered in the southern city of Karachi. Wall Street Journal correspondent Daniel Pearl was kidnapped there in January and later murdered.

On May 8, a bomb exploded in front of a Karachi hotel, killing 11 French engineers and three others, including the suicide bomber. Another explosion killed 12 Pakistanis outside the U.S. Consulate in Karachi on June 14.

The Taxila hospital is supported by the Presbyterian Church USA and the Presbyterian Church of Pakistan. It was founded in 1922 and treats mostly poor Muslims, specializing in eye diseases. Following the attack, outpatient services were suspended for the day.

“We never thought we would be a target,” said Ernest Lall, former director of the hospital. “We have been here since 1922, and someone throws a bomb. I don’t know why.”