Pressure on Musharraf after attacks

Security has been stepped up at churches and diplomatic missions around the country

ISLAMABAD, Pakistan (CNN) -- Pakistani President Pervez Musharraf has sacked Islamabad's two most senior police officers in the wake of Sunday's church grenade attack in the capital.

Musharraf, under pressure to improve security in the South Asian nation, summoned together top security officials in a meeting on Tuesday to review law and order.

The Pakistani leader had expressed dismay over the over the security lapse that allowed grenades to be set off in a church in the heart of Islamabad's diplomatic compound, killing five people.

Musharraf removed the city's inspector general and superintendent of police, officials told Reuters news agency on Tuesday.

No group has yet claimed responsibility for the attack but the focus has fallen on Muslim militants opposing Musharraf's crackdown on religious extremism and his close alliance with the United States.

DNA testing

VIDEO U.S. President George Bush says he is "outraged." CNN's Major Garrett reports. Play video (QuickTime, Real or Windows Media) U.S. and Pakistani officials suspect that anti-U.S. sentiment is behind the attack. CNN's Ash-Har Quraishi reports. Play video (QuickTime, Real or Windows Media)   PHOTO GALLERY Pakistan church attack    MORE STORIES • U.S. weighs up Pakistan 'departure'  • Officials: Militants trying to divide U.S., Pakistan     RESOURCES On the Scene: Gruesome scene at Pakistan church     CNN.com Asia More news from our Asia edition

Two Americans, a Pakistani national and an Afghan were killed in the attack on Sunday morning during a service at the Protestant International Church in Islamabad. A fifth body has not been identified. At least 45 others were injured.

Security has been stepped up at churches and diplomatic missions around the country and Musharraf has vowed to bring the attackers to justice.

Pakistan was sending DNA samples of the unidentified body to the United States in the hope of more leads in the investigation, the Associated Press reported on Tuesday.

No one among the congregation at the time of the attack has been reported missing and police are suspicious that the body may have been the man who carried out the attack.

The two Americans killed have been identified as Barbara Green and her 17-year-old daughter, Kristen Wormsley. Green worked at the U.S. Embassy. Arrangements were being made to send their bodies back to the United States.

In a brief phone call Monday with President Bush, Musharraf expressed his condolences and "his sympathy for the loss of lives and the wounded," a Bush administration official said.

Security concerns

During the call, which lasted about five to 10 minutes, the two leaders also discussed the war against terror, the official said. Pakistan has supported the United States in its battle against the Taliban and al Qaeda in Afghanistan and the global fight against terrorism.

In a statement Sunday, Bush expressed outrage over the attacks, and Secretary of State Colin Powell said the United States and Pakistan "are determined to see the guilty parties swiftly brought to justice."

White House officials blamed the attack on Islamic militants trying to drive a wedge between the United States and Musharraf.

The Pakistani leader said the attack was an attempt to undermine his effort to crack down on militancy and terrorism.

But the church raid has raised concern that law and order throughout Pakistan was waning.

Three people were gunned down in Lahore on Tuesday and there has been an increase of attacks on minority Shia Muslims in recent weeks.

Army troops -- usually deployed during the Muslim holy festival of Moharram, which began on the weekend -- are fewer in number because of Pakistan's border military build-up with India.