Iraqi forces declared an end to the Islamic State's caliphate. The announcement came Thursday morning from the northern Iraqi city of Mosul, inside the ruins of the city's grand mosque, where the fighting has been ongoing for more than 250 days.

"Their fictitious state has fallen," military spokesperson Brigadier General Yahya Rasool told state TV on Thursday - three years to the day since ISIS leader Abu Bakr al-Baghdadi declared the establishment of the so-called caliphate from the same spot.

“We are seeing the end of the fake Daesh state,” Iraqi Prime Minister Haider al-Abadi said in an statement on his Twitter account Thursday.

The capture of the 850-year-old Grand al-Nuri Mosque is a major symbolic victory for the Iraqi forces.

However, Iraqi authorities expect the long battle for the entire city to continue for several days since the remaining Islamic State fighters are held up in several areas of the city.

Lt. Gen. Abdul Wahab al-Saadi told The Associated Press elite special troops entered the compound and took control of the surrounding streets on Thursday afternoon after a dawn offensive.

The site will need to be cleared by explosives experts as ISIS often rigs areas it has retreated from with booby traps.

