Iraqi special forces have entered the outskirts of Mosul, taking the state television building and advancing despite fierce resistance by Islamic State (IS) fighters who hold the city.
The advance marks the first time Iraqi troops have set foot in the city, Iraq's second largest, in more than two years.
It marks be the start of a gruelling operation for the troops, who will be forced to engage in difficult, house-to-house fighting in urban areas which is expected to last weeks, if not months.
Troops entered Gogjali, an area inside Mosul's city limits, and by noon were roughly 800 yards from the more built-up Karama district, according to Maj. Gen. Sami al-Aridi of the Iraqi special forces.
"The special forces have stormed in," he said. "Daesh (another term for IS) is fighting back and have set up concrete blast walls to block off the Karama neighbourhood and our troops' advance."
Bombs have also been laid along the road into the city, he added.
Later, Maj Gen al-Aridi said the troops had taken the nearby state television building, the only one in the province, and that heavy fighting broke out when they tried to press on into built-up areas.
Mosul is the final IS urban bastion in Iraq, the city from which it drove out a larger but demoralised Iraqi army in 2014 and declared a "caliphate" that stretched into Syria.
Its loss would be a major defeat for the jihadis, but with the closest Iraqi troops still some six miles from the city centre, much ground remains to be covered.
The battle opened up with Iraqi artillery, tank and machine gun fire on IS positions on the edge of Gogjali, with the extremists responding with guided anti-tank missiles and small arms in an attempt to block the advance. Air strikes by the US-led coalition supporting the operation added to the fire hitting the district.
Spokesman Col John Dorrian said that the coalition, which coordinates all its attacks with the Iraqis, has been observing the battlefield and has noted that IS forces can no longer move in large numbers.
"And when we see them come together where there are significant numbers we will strike them and kill them," he said.
Concerns over civilian casualties have led to air operations using precision munitions only, he added.
From the nearest village east of Mosul, Bazwaya, smoke could be seen rising from buildings in Gogjali, where shells and bombs had landed. IS fighters also lit special fires to produce dark smoke in order to obscure the aerial view of the city.
Inside the village, white flags still hung from some buildings, put up a day earlier by residents eager to show they would not resist the Iraqi forces' advance. Some residents stood outside their homes, and children raised their hands with V-for-victory signs.
The families, estimated to number in the hundreds, will be evacuated from the village to a displaced persons camp, according to Brig. Gen. Haider Fadhil of the Iraqi special forces.
As the fighting raged, several of the newly displaced from Bazwaya could be seen carrying white flags and driving a herd of some 150 sheep toward the camp.
For more than two weeks, Iraqi forces and their Kurdish allies, Sunni tribesmen and Shia militias have been converging on Mosul from all directions to drive IS from the city.
Iraqi forces have made uneven progress in closing in on the city. Advances have been slower to the south, with government troops still 20 miles away. To the north are Kurdish forces and Iraqi army units, and Shia militias are sweeping toward the western approach in an attempt to cut off a final IS escape route.
The Shia forces, Iran-backed troops known as the Popular Mobilisation Units, are not supposed to enter Mosul, given concerns that the battle for the Sunni-majority city could aggravate sectarian tensions.
Just behind the eastern front line, the army's ninth division has moved toward Mosul on the path cleared by the special forces, and was now approximately two miles from its eastern outskirts.
The US military estimates IS has 3,000-5,000 fighters in Mosul and another 1,500-2,500 in its outer defensive belt.
The total includes about 1,000 foreign fighters. They stand against an anti-IS force which - including army units, militarised police, special forces and Kurdish fighters - totals more than 40,000 men.
As the Mosul offensive has pressed on, bombings have continued in the capital, Baghdad - part of sustained IS efforts to destabilise the country.
Dozens have been killed since the push on Mosul started in apparent retaliation attacks, mostly claimed by IS.
Violence is still rampant across the country, with killings worsening in October, the United Nations said.
In a monthly report released by the Assistance Mission for Iraq, it said 1,792 people were killed in violence in Iraq in October, up from 1,003 the previous month. Around 1,120 of the dead were civilians.
The worst-hit city is Baghdad with 268 civilians killed and 807 wounded, while the militant-held Ninevah province comes next with 566 killed and 59 wounded.
The UN did not say whether the Mosul operation was directly related to the casualties in Ninevah, its surrounding province.
Meanwhile, Kurdish authorities detained a Japanese freelance journalist covering the fighting. The Kyodo News agency said Kosuke Tsuneoka was reporting on the battle to recapture the city of Mosul from the Islamic State group. He is being held by Kurdish fighters known as the peshmerga.