Islamist militants continued their violent offensive in Iraq Thursday, inching closer to the capital and sending thousands of ethnic minorities fleeing to the mountains. 

The Islamic State of Iraq and Syria (ISIS) continued to seize areas of northern Iraq, causing international alarm and humanitarian concern. 

ISIS fighters are controlling a checkpoint at the border area of the region, which is a Kurdish, semi-autonomous region close to Arbil, a major city that houses the Kurdish regional government. 

The Sunni militants captured Qaraqosh, Iraq's biggest Christian town, earlier this week, causing residents to flee out of fear of persecution. Christians are left with little options, and are forced to either evacuate, convert to Islam or be killed, according to Reuters. 

ISIS, which is al-Qaeda affiliated and considered even more extreme than al-Qaeda, views the ethnic minorities in Iraq -- Shiites, Christians and Yazidis, a Kurdish religious minority -- as infidels. They believe they should convert to Islam or face death. 

The defeat of the Kurdish forces over the weekend caused tens of thousands of Yazidis to flee to the mountains in the town of Sinjar.  

Pope Francis called on world leaders to put an end to what he called "the humanitarian tragedy" in northern Iraq, and France called an emergency meeting of the U.N. Security Council to consider options on how to combat ISIS. 

ISIS said in a statement on Twitter that it has captured 15 towns, a military base and the Mosul dam, which is a strategic location on the Tigris River. 

The shares of energy companies operating in the region fell after news broke that the group had captured lucrative oilfields. 

On Thursday, Reuters reported that ISIS put their black flag over the dam. The capture of the dam allows militants to either flood or cut off electricity and water supplies to cities. 

Some of the thousands of ethnic minorities who are trapped in the mountains in Sinjar were rescued in the yesterday, according to the U.N. Office for the Coordination of Humanitarian Affairs. Around 200,000 minorities have fled to the mountains due to the conflict. 

"This is a tragedy of immense proportions, impacting the lives of hundreds of thousands of people," U.N. spokesman David Swanson told Reuters. 

He said that the people are in dire need of food, water, shelter and medicine. He said that as many as 40 children have died from dehydration in the mountains. 

Yazidis are seen as "devil worshippers" by ISIS, who is trying to establish an Islamic empire. 

Thousands of Yazidis are fleeing to Turkey to seek asylum. 

ISIS is continuing to wage war against Kurdish forces in an effort to capture more areas of Iraq.

Eleven people were recently killed in Kirkuk, a strategic oil town in the north, by two car bombs that exploded near a Shiite mosque. A car bomb also exploded in a Shiite area of Baghdad, killing 14. All in all, car bombs in crowded Shiite markets have killed 59 and wounded 125.  

The Islamic State has also seized a border town in Lebanon, raising fears that militants in the Arab world will join their cause and expand their offensive against non-Islamists. ISIS declared a caliphate in areas of Syria and Iraq. 

On Wednesday, the militants also clashed with Kurdish forces in Makhmur, southwest of Arbil. While witnesses said the militants seized the town, officials said the Kurdish peshmerga forces are still in control in the region. 

ISIS is the biggest threat to Iraq's security since the fall of Saddam Hussein in 2003. The militant group has worsened sectarian fighting, causing the situation to mirror the civil war that peaked in 2006 and 2007 when the U.S. still occupied Iraq. 

Kidnappings, bombing and executions are once again frequent, leaving religious and ethnic minorities particularly vulnerable. 

The militants have been driving Shiite Muslims from towns in Nineveh, and last month, they set a deadline for Christians to either leave Mosul or face certain death. 

The Sunni militants seek to kill all non-Sunni Islamists, and Shiites in particular, as they believe Shiites receive unwarranted power in Prime Minister Nuri al-Maliki's predominantly Shiite government. 

However, al-Maliki has refused calls to give up his bid for a third term. He said the process of choosing a new prime minister would open the "gates of hell" in the already fractured country.