The Islamic State group launched a massive attack on Kurdish forces southwest of Erbil in Iraq Tuesday night. The fighting has continued for hours and coalition aircraft have been unable to fire on ISIS militants due to the close proximity of each side on the ground, CNN reported, citing Kurdish officials.

The terror group -- formerly known as ISIS or ISIL -- launched the first assault around 9 p.m. local time about 28 miles from Erbil, the Kurdish capital. ISIS has made almost daily efforts to break through the Kurdish lines, which are spread out along the River Zab, according to CNN.

ISIS fighters launched the offensive attacks on Kurdish units at close quarters from several directions near the towns of Gwer and Makhmour. Kurdish militia known as peshmerga have placed large concrete barriers across the highway, which was once the main road between Irbil and Mosul. But the barriers are susceptible to mortar fire and suicide bombs. Kurdish peshmerga soldiers have said they lack modern weaponry and essential equipment that would help defeat ISIS, according to CNN.

Kurdish officials told CNN that they are concerned the Islamist militants will break through their lines, which would leave little between ISIS and Erbil. That city in Iraqi Kurdistan has been one of the only havens in the entire region that hasn't been overun by Islamic State fighters.

Kurdish forces are already stretched across several areas, particularly in Mosul, which ISIS seized in June. Peshmerga soldiers have recently tried to surround Mosul in an effort to cut off ISIS supply lines from Syria and set up an offensive to recapture the city. The United States is training Iraqi units, which could be ready to launch an attack on the ISIS-controlled city by the summer.