The bombing of the Hamas government headquarters in Gaza City also set off explosives that were stored at the site, IDF officials said Saturday examining footage of the aerial strike. The army explained that the building was used to plan terror attacks and served as a base for rocket-launching cells. Related articles: Jabari praised in Arab sector protests IDF kills 9 Palestinians in Gaza 'Attacks on Tel Aviv encourage Gazans' The 4-storey building, which housed Hamas Prime Minister Ismail Haniyeh's office, was completely destroyed. An IDF official said the building was apparently empty at the time of the attack early Saturday morning. Egyptian Prime Minister Hisham Kandil met with senior Hamas figures in the building on Friday during his snap visit to Gaza. Following the attack Haniyeh tweeted: "The Zionists believe their attack will weaken us, but the opposite is true. It only strengthens our determination to liberate Palestine and increase deterrence in the face of the Zionist settler until we achieve victory." Hamas spokesman Ihab Al Ghussein said following the attack that "Israel believes this will weaken us, but it only gives us more power and determination." Israeli aircraft bombed three key Hamas buildings overnight. Apart from the government building, jets targeted a police station in Gaza City and a structure belonging to Hamas' internal security service. Despite the attacks, dozens of rockets have been fired toward south Israel overnight and during the early morning hours. Follow Ynetnews on Facebook and Twitter Receive Ynetnews updates directly to your desktop