As the Islamic State group fights to defend Mosul, its last remaining stronghold in Iraq, it has massacred civilians fleeing the city and hung their bodies from electrical poles, the Kurdish Security Council said Friday.

According to the Council, the Islamic State, also known as ISIS, killed 140 civilians who were fleeing the besieged city and hung their bodies on electrical poles in the neighborhoods of Eslah Zirai and Tanak on Monday and Tuesday. Some other bodies were taken to the frontline, the Council said in a series of tweets. The reports have not been independently confirmed.

Read: US War Crimes In Iraq? Russia Wants UN Meeting After Airstrike Kills 200 Civilians In Mosul

The U.S. military joined the Iraq Army and Kurdish forces in an offensive to take back the northern city of Mosul in October, after the Islamic state controlled the city for two years. Nearly half a million civilians are still thought to be living in Mosul, which is under attack by Iraqi forces and coalition airstrikes.

Civilians are fleeing the city and "running for their lives," the New York Times reported last week, while avoiding ISIS car bombs and explosives falling from the sky. On March 17, a coalition airstrike killed 200 civilians in the city. A senior Iraqi military officer said the strike hit an ISIS truck filled with explosives.

In January, Iraq security forces took back the eastern part of the city, where schools have reopened and children are playing in the streets again. But ISIS has used drones to attack the civilian population there and have also launched mortar strikes against the eastern side of the city from across the Tigris river, which runs through the center of Mosul.

Mosul is just 70 miles from the Syrian border. On Wednesday, ISIS executed 33 people with "sharp tools" in eastern Syria, according to the Syrian Observatory for Human Rights.