In a second incident, shots were fired on the office of a Lebanese minister of state, shortly after Gemayel's death.
"The office of the state minister for parliamentary affairs, Michel Pharaon, in the Ashrafieh neighbourhood was the target of gunshots today from gunmen in a white Suzuki car," Pharaon's office said.
"The security forces cordoned off the area and is carrying out the necessary measures to identify the culprits" who fled the scene.
Pharaon is a Greek-Catholic Christian MP from the majority anti-Syrian parliamentary bloc.
Speaking to Al Jazeera on Tuesday, Samir Geagea, leader of the predominantly Christian-backed Lebanese Forces, said the governing bloc "will not permit a return to the situation that prevailed before March 14 of last year".
He noted that Hezbollah and the other parties that he described as co-operating with Syria, were standing in the way the international tribunal for trying the al-Hariri assassination case.
He demanded that the Lebanese president, Emile Lahoud, step down, adding that "the deteriorating situation in Lebanon is only providing political cover to certain parties that want to wreak havoc in Lebanon".
For his part, Walid Jumblatt, the Druze leader and a leader of the March 14 camp, said the UN tribunal for trying al-Hariri's assassination case would ultimately be formed and that the Lebanese should beware of getting embroiled in an internal conflict.