Sunni Islamist militants from the Islamic State in Iraq and the Levant (ISIS) have rapidly expanded their control of Iraq as a whole. The group is now said to be within range of overtaking Iraq’s biggest oil refinery in the city of Baiji.

The Baiji refinery can produce over 300,000 barrels of oil per day and supplies oil to the majority of Iraq. The refinery is also tasked with supplying power to Baghdad, Iraq’s capital city. Iraq is OPEC’s second biggest oil producer.

Baiji is a city 130 miles north of Baghdad with an estimated population of 200,000.

Security sources told Reuters that the ISIS jihadists drove into Baiji, the home of the refinery, with a caravan of armed vehicles. The militants then proceeded to burn down the court house and police station, and freed masses of prisoners from jails.

The jihadis have guaranteed safe passage if the 250 men guarding the oil refinery agree to lay down their weapons and leave.

A resident of Baiji told Reuters that ISIS has tried to persuade military and police officers not to resist their intrusion into the territory. The resident said, “Yesterday at sunset some gunmen contacted the most prominent tribal sheikhs in Baiji via cellphone and told them: ‘We are coming to die or control Baiji, so we advise your sons in the police and army to lay down their weapons and withdraw before evening prayer’.”

The infiltration of Baiji came mere hours after ISIS militants overtook Mosul, Iraq’s second largest city. During the recent raids, More than 150,000 Iraqi soldiers have darted from their positions, leaving behind advanced weaponry and supplies. ISIL now has tanks and helicopters as part of its fighting apparatus.

ISIS is an Al Qaeda-offshoot that seeks to create a Sharia law compliant Sunni Islamic caliphate that runs through both Iraq and Syria.