Hamas HQ Reduced To Rubble Unfortunately your browser does not support IFrames. Watch More News Videos at ABC | 2012 Presidential Election | Entertainment & Celebrity News ABC NEWS: In the early hours of Saturday morning, Israel's Air Force reduced the headquarters of the militant group Hamas to rubble. It was one of several Hamas buildings and homes targeted, part of Israel's continuing effort to destroy the group's command and control structure as speculation mounts over an Israeli ground invasion. The Israel Defense Forces released aerial drone video of the attack on the government building, the seat of Hamas Prime Minister Ismail Hanniyeh. Israeli warplanes have also struck the main police station, the interior ministry and the homes of top Hamas leaders. As of Saturday morning, almost 900 "terror sites" had been targeted by Israel, including weapons caches and rocket launching sites. Around 600 rockets have been fired into Israel by Hamas and other militant groups, around a third of which were intercepted by the Iron Dome anti-missile system, according to the Israeli military. The loud thud of Israeli missiles hitting Gaza and the buzz of drones overhead were consistent on Saturday, as Israeli tanks and troops massed on the border in preparation of a ground invasion. Israeli media also reported that 20,000 reservists have been called up.