ISIS militants, who have seized control of the Iraqi cities of Mosul and Tikrit, captured two additional towns north of Baghdad this morning but have yet to invade the capital city.

Again, Iraqi troops stationed in both areas failed to fight back against the Sunni insurgents, who arrived in the towns of Jalula, located 80 miles northeast of Baghdad, and Sadiyah, 60 miles north of the city, armed with machine guns. The Associated Press describes the scene:

Residents reached in Jalula said the gunmen issued an ultimatum to the Iraqi soldiers not to resist and give up their weapons in exchange for safe passage out of the city. After seizing the city, the gunmen announced through loudspeakers that they have come to rescue residents from injustice and that none would be hurt.

The militants failed to uphold that last claim in Mosul, where they vowed to instate sharia law. United Nations human rights spokesperson Rupert Colville told Reuters that hundreds of people may have been killed in the city since the siege. Reuters reports

He said his office had reports the killings included the execution of 17 civilians working for the police and a court employee in central Mosul. Four women had killed themselves after being raped, 16 Jordanians had been kidnapped, and prisoners released by the militants had been looking to exact revenge on those responsible for their incarceration, he said.

Men volunteer to fight ISIS in Baghdad. AP/ Karim Kadim

Colville added that up to 30 civilians might have been killed by government forces, who may have "committed excesses" in their fight against the militants. Human Rights Watch also warned that the advance of ISIS, which has a reputation for violence, poses a major threat to Iraqi civilians.  

Iran said overnight that it will help Iraq fight off the militants. The alliance would be troubling to the U.S., which said that it is contemplating air strikes on militant enclaves but won't put boots on the ground. "We do have a stake in making sure that these jihadists are not getting a permanent foothold," President Barack Obama said on Thursday.

Ben Rhodes, the president's deputy national security advisor, added that "the president is mindful that the United States has sacrificed a lot in Iraq and we need to not just be taking this all back on ourselves... we need to come up with solutions that can enable the Iraqis to manage their internal security and their internal politics." In addition to providing possible military assistance, Washington will send the country about $12 million in humanitarian aid.

The escalating situation threatens to increase sectarian tensions in the region, pitting Sunnis agains Shiites in a sprawling, border-crossing conflict.