ISIS terrorists are stealing civilians' cars in an attempt to flee as Iraqi soldiers fight their way into the strategically important city of Tikrit. The massive operation involving more than 30,000 Iraqi Army soldiers is succeeding in forcing ISIS militants from the city, which is the birthplace of former Iraqi dictator Saddam Hussein. Local officials confirmed that Iraqi troops entered Qadisiya, and penetrated the northern suburbs, raising the Iraqi flag over Tikrit's general hospital. Scroll down for video . A member of the Iraqi forces poses with an Iraqi flag in Tikrit - taking the city would open a supply line for a future operation to besiege Mosul, Iraq's second-largest city that still remains under ISIS control . Iraqi forces entered the city and succeeded in driving out ISIS terrorists from the crucial stronghold . Later today, Iraqi forces (including the military, militias, Sunni tribes and police) also entered Tikrit from the south in a pincer movement to try and drive out the terrorists, although many fled in the face of the advance. 'The terrorists are seizing the cars of civilians trying to leave the city and they are trying to make a getaway,' Kheyon Rasheed told the state-run Iraqiyya television. Tikrit, which lies midway between regime-capital Baghdad and the ISIS stronghold of Mosul, was taken by ISIS in June. Retaking the ISIS stronghold is considered vital if government forces are to succeed in their plan to force ISIS out of the oil rich city of Mosul, the terror group's Iraqi power base which lies just 140 miles north of Tikrit on Highway 1 - a road that effectively marks the front line in northern Iraq. Most residents of Tikrit fled in the months after the extremist group took control. Those who stayed have fled in recent days, but a tiny fraction are still there, awaiting their fate. Iraq forces entered ISIS-held Tikrit city centre from Qadisiya in the north and also from the south - the terrorists still hold the town of al-Alam, north of Tikrit university . Militiamen laid down heavy machine gunfire in the neighborhood's dusty streets during the attack today . Taking Tikrit would open a supply line for a future operation to besiege Mosul, Iraq's second-largest city that still remains under ISIS control . Tikrit would be the biggest victory yet for Iraqi forces, but the attack by thousands of Shi'ite irregulars could severely test the government's ability to handle sectarian divisions. Iraq is bitterly split between minority Sunnis, who were an important base of support for Saddam Hussein, and the Shi'ite majority. Since the Islamic State insurgency began, the Iraqi military is heavily dependent on Shi'ite militias that have been accused of abusing Sunni communities elsewhere in Iraq. US military officials - who have not been involved in the ongoing Tikrit offensive - have that said a coordinated military mission to retake Mosul is likely to take place next month or two and involve up to 25,000 Iraqi troops. But the Americans have cautioned that if the Iraqis are not ready, the offensive could be delayed. Iranian military advisers have been helping guide Iraqi forces in their advance on Tikrit. General Qasem Soleimani, the commander of Iran's Islamic Revolution Guards Corps (IRGC) Quds Force, is taking part in leading the Tikrit operation. Most battlefield successes in Iraq have been coordinated efforts, with Iraqi, Kurdish and Shiite militias fighting on the ground and the US-led coalition providing air power. The siege on the village of Amirli just north of Baghdad, when many feared the capital itself might fall, was broken last year with the help of US-led airstrikes and a fighting force of mainly Shiite militias. Shiite militiamen, backed by a coalition air campaign, also retook the town of Jurf al-Sukhr, on Baghdad's outskirts, from the militants in October. Iraq's Prime Minister Haider al-Abadi has appealed for more aid for his country's beleaguered ground forces, despite the US spending billions of dollars training and equipping Iraq's army during its eight-year occupation. Tikrit, the capital of Salahuddin province, sits on the Tigris River about 80 miles north of Baghdad . Armoured vehicles of Iraqi security forces drive past black smoke following the clash with ISIS . Iraqis celebrated the advance on Tikrit and the withdrawal of ISIS militants from the city . Tonight, Iraqis in Baghdad celebrated the news from Tikrit where ISIS militants fled the city in civilians' cars . The rapid advance across Syria and Iraq by militant fighters from ISIS in 2014 led to the jihadist group announcing the establishment of a 'caliphate' - stretching from Aleppo in Syria to the province of Diyala in Iraq by June. The US went on to assemble a coalition to fight the militants, and has so far launched more than 1,400 air strikes against IS targets in Iraq since the campaign started on August 8. Meanwhile, the UK launched its first air strikes on September 30.
ISIS stealing cars to flee as Iraqi soldiers enter stronghold of Tikrit . Iraqi forces closing in on city centre that has been held by ISIS since June . Retaking ISIS stronghold vital if forces are to force ISIS out of Mosul . Mosul is the terror group's Iraqi power base and is 140 miles north of Tikrit .