Iraq's largest Sunni-Arab political party on Wednesday condemned a car bomb attack inside Baghdad's heavily fortified Green Zone that apparently attempted to kill Iraq's controversial speaker of parliament. The small bomb exploded Tuesday afternoon at the back of an armored car in the motorcade of the Sunni speaker, Mahmoud al-Mashhadani, as it was driving into a parking lot near the Green Zone's convention center, where al-Mashhadani and other Iraqi legislators were meeting, a parliamentary aide said. The slightly wounded American security guard driver got out of the vehicle and found other explosive devices planted beneath it, the aide said on condition of anonymity because of the sensitivity of the issue. The driver called US soldiers, who brought bomb-sniffing dogs to the scene. The dogs detected explosives in another vehicle in the area belonging to al-Mashhadani's motorcade, said Lt. Col. Christopher Garver, a US military spokesman. Bomb specialists detonated that car, which set off a series of blasts that caused a fire but injured no one and caused no major damage to nearby structures, Garver said. The blaze was put out by the Green Zone's fire department. "Obviously, we take security very seriously, so we are investigating this incident," Garver said Tuesday. The serious security breach in the Green Zone - which houses the Iraqi government, the US and British embassies and thousands of foreign troops and private contractors - forced the Iraqi legislators to stay inside the convention center for several hours until the fire was put out and the area found to be safe, the aide said. "We strongly condemn this act," Ammar Wajih, the chief spokesman for the Iraqi Islamic Party, the largest Sunni-Arab part in Iraq, told The Associated Press on Wednesday. "To plant a bomb in a heavily guarded place near the parliament building is a big security breach because few authorized persons can enter this area. The aim of this act is to hamper the political process."