Baghdad, Iraq (CNN) -- A bomb killed at least four people and wounded 25 others in one of Iraq's holy cities Wednesday morning, an Interior Ministry official said.
The bomb detonated in a popular restaurant in Karbala at 8:30 a.m., when it was packed with breakfast diners.
The restaurant is about 400 meters (one-quarter mile) from the headquarters of the city's security forces, said Karbala police spokesman Abdul Rahman al-Meshawi.
The attack came as Iraq prepares for the Muslim feast of Eid al-Adha, which begins Friday. Authorities have beefed up security measures for the five-day holiday, which has in the past served as prime time for insurgents to carry out high-profile attacks.
Karbala, about 60 miles southwest of Baghdad, is revered as the home to a shrine honoring Imam Hussein, the grandson of the Prophet Mohammed and a venerated Shiite martyr.