An explosion in the wake of an airstrike is seen in a western neighborhood of the besieged Syrian city of Kobani Nov. 23, 2014. Reuters/Osman Orsal

The Islamic State group Saturday mounted an assault on the Syrian border town of Kobani, reportedly from within Turkey. The struggle began when a suicide bomber detonated an armored vehicle as it approached a border crossing between Kobani and Turkey, the Associated Press reported.

The group, also known as ISIS, is attacking Kobani from all sides, Kurdish Democratic Union Party spokesman Nawaf Khalil told the AP. Approximately 40 people on both sides, the Syrian Kurdish fighters and ISIS militants, were killed in Saturday's fighting.

ISIS has been fighting for control Kobani for about two months as the group aims to build its self-declared caliphate. ISIS already has taken over wide swaths of Syria and Iraq.

Several questions have been raised in the siege, notably, about whether U.S. efforts to aid in the fight against ISIS are working, but primarily about whether Turkey is involved with ISIS, which Turkey denies. Turkey has hesitated to help Kobani because it does not want to incite a Kurdish nationalist movement in its own country, the Hill reported.

While reports say the attack was launched from Turkey, Ankara called the reports inaccurate. "Claims that the vehicle reached the border gate by crossing through Turkish soil are a lie," the Turkish government said in a statement.

However, witnesses in Kobani reported seeing attacks from the Turkish border. Activist Mustafa Bali told the AP he saw ISIS fighters in “grain silos on the Turkish side of the border … launching attacks towards the border crossing.”