Witnesses in Jounieh, in the Christian heartland 10 miles north of Beirut, said the explosion occurred near the main square of the picturesque town. It took place near the office of Sawt al-Mahabba, a Christian religious radio station, and a Maronite Catholic church at the entrance to the old souk, or market.

Earlier in the day, the radio station had aired live broadcasts of a sit-in by relatives of Lebanese prisoners held in Syrian jails.

Police officials estimated the bomb at 44 pounds of explosives but could not immediately tell whether it was placed in, under or next to a car on the street.

The explosion, heard as far away as the hills overlooking the Mediterranean coast at about 9 p.m., shattered windows of apartments and cars in the old town, a mix of old stone buildings housing shops and residential apartments.

Flames shot up from the first floor of a building above the Cheaper Shop, a one-dollar store whose shutters were blown out by the force of the explosion. Fire engines rushed to the scene, maneuvering their way through the narrow alleys of the old town on the Bay of Jounieh.

Abdo Abou Jaoude, sound technician at the station, was trapped for three hours before rescuers were able to free him from under the stones and concrete blocks.