At least 744 Christian families, or about 3,750 people, fled the city dubbed by U.S. and Iraqi commanders as the last urban stronghold of Al-Qaeda for refuge with relatives in churches and at Christian centers in several towns and villages to the north and east of Mosul, according the U.K-based persecution watchdog ministry Barnabas Fund.
Some are even sleeping in their cars.
These displaced Iraqi Christians are said to be in desperate need of food, clothing, bedding, personal hygiene items and other basic necessities.
"We left everything behind us. We took only our souls," said Ni'ma Noail, 50, a civil servant who was forced by the violence to abandon his home in Mosul and is now living in a church, according to Barnabas Fund.
The United States on Tuesday condemned attacks on Iraqis, including those against Christians in Mosul.
"The terrorist groups responsible for these attacks have shown again that their enemy is the Iraqi civilian population," the U.S. embassy said in a statement. "They are seeking to create divisions among Iraqi communities and undermine the progress Iraq is making in building an inclusive, democratic and prosperous society."
Mosul, the capital of Ninewa province, is home to the second-largest Christian community in Iraq, after Baghdad. Many Christians from Baghdad and Basra had fled to the north for safety in recent years.
The original city of Mosul lies on the west bank of the Tigris River, opposite the ancient biblical city of Nineveh on the east bank. Mosul contains the tombs of several Old Testament prophets, including Jonah and Nahum.
Last week's mass exodus from Mosul was triggered by the heightened violence targeted at Christians recently. More than a dozen Christians were murdered in the last two weeks alone, including three people within a 24 hour period last Tuesday.
Bullet-riddled bodies of Christians killed by unknown assailants were regularly found in different neighborhoods in Mosul. The latest death was of a Christian music store owner shot dead on Sunday.
Gunmen had stormed into his store in the eastern part of the city, killing him and wounding his teenage nephew, a police officer reported Monday, according to The Associated Press.
Also, leaflets have been distributed in Mosul threatening Christians with death unless they converted to Islam or pay the Islamic jizya tax for non-Muslims, Barnabas Fund reported.
"The situation in Iraq is extremely grave. Sunni Muslim extremists are moving north, now that they have successfully managed to intimidate and drive out most of the Christians from the cities of Basra in the south and Baghdad in the center of Iraq," said Dr. Patrick Sookhdeo, international director of Barnabas Fund.
He appealed to the Iraqi government and the U.S. army to quickly intervene to "prevent the elimination of the indigenous Christian community" in Iraq.
"I also appeal to Christians around the world to help meet the practical needs of their Iraqi brothers and sisters at this time through the ministry of Barnabas Fund," said Sookhdeo, a former Muslim and now a much sought-after expert on jihadist ideology.
The "major displacement," as the governor of Ninewa province calls it, follows devastating news that the Iraqi Parliament recently voted to drop a clause in its new provincial election law that would essentially silence the Christian voice in Iraq.
Article 50, which was removed, reserved seats on Provincial Councils for Christians and other minorities to ensure they are represented in the government.
Some Iraqi Christians accuse the government of trying to push the remaining Christians to leave Iraq.
"They want us to feel that we are no longer Iraqis," worshipper Afram Razzaq-Allah said after a services at a Catholic church in Baghdad, according to AP.
Since the U.S.-led Iraq war in 2003, more than 200 Christians have been killed, dozens of churches bombed, and more than half the Iraqi Christian population has left the country.
U.N. special representative Staffan de Mistura expressed concern Monday about the rising violence targeted at Christians in recent days, and has called for the Parliament to reinstate Article 50.