Sialkot, Pakistan ? A suicide attacker carrying a bomb in a briefcase struck a Shiite mosque crammed with hundreds of worshippers in eastern Pakistan, killing at least 25 people and wounding more than 50 during Friday prayers.

Shortly after the attack, experts defused a second bomb outside the mosque, where hundreds of angry Shiites had gathered to protest the attack.

No group claimed responsibility for the bombing. But a prominent Shiite cleric speculated it was in retaliation for the killing by security forces of a Sunni militant and top al-Qaida operative accused in the beheading of American reporter Daniel Pearl.

President Gen. Pervez Musharraf, a key U.S. ally, said the bombing showed “terrorists have no religion and are enemies of mankind.” He renewed his government’s commitment to root them out.

In the three years since Musharraf threw Pakistan’s support behind the U.S.-led war on terror, Islamic militants, often linked to al-Qaida, have launched repeated attacks against the government and Western targets.

Violence has also been directed at Shiites, who make up about 20 percent of Pakistan’s 150 million people, most of whom are Sunni Muslims. As in Iraq, where Sunni militants are suspected of carrying out provocative attacks on Shiites, sectarian tensions linger close to surface in Pakistan.

The blast at 1:26 p.m. — during prayers for the Muslim sabbath — left a crater in the Zainabia mosque in the center of Sialzot and damaged its walls.

Witnesses said a man with a briefcase entered the mosque shortly before the blast carrying a briefcase which then exploded, Sialkot police chief Nisar Ahmed said.

“I was praying when I first saw a bright light and then something exploded with a big bang, and I fell down,” said Sajjad Anwar, 36, who was being treated at a hospital.

“I saw human body pieces hitting the walls and ceiling of the mosque,” he said.

Another injured, Mumtaz Ali Shah, 43, said: “My mind stopped working for a while after the blast, but when I opened my eyes, I was lying among dead bodies.”

Earlier, 26-year-old Mohammed Nawaz, who lives near the mosque, told AP: “When I came out of my home and went to the mosque, I saw a doomsday scenario. People were crying, pieces of body and blood were scattered everywhere inside the mosque.”