Syrian government and allied forces seized large parts of an important district in rebel-held eastern Aleppo on Saturday but fierce fighting for control of the residential area continued, rebels, pro-government media and a monitor said.

Government forces have advanced with a ground and air assault on the edge of the besieged eastern half of the city, a move the rebels say is designed to split their most important urban stronghold in two.

Aleppo, which was Syria’s biggest city before the start of a civil war that has killed hundreds of thousands of people, is divided between the government-held west and rebel-held east, where U.N. officials say at least 250,000 people are under siege.

Capturing all of Aleppo would be a major victory for Syrian President Bashar al-Assad after six and a half years of fighting.

A Syrian military source and the Britain-based Syrian Observatory for Human Rights war monitor said Syrian government and allied forces had taken control of about 80 percent of the Hanano housing district, which is on the northeast frontline of the eastern sector.

A renewed air assault on residential and frontline parts of east Aleppo began last Tuesday after a weeks-long pause in air strikes and shelling there.

Yasser al-Yousef, from the political office of the Nour al-Din al-Zinki rebel group, said insurgents had been fighting fiercely for the past 48 hours to defend Hanano and the southern front of east Aleppo from heavy government bombardment.

“The regime managed to advance into a number of positions in the Hanano housing area but revolutionary fighters are trying to take them back,” Yousef said.

The Syrian military source said the army hoped to fully secure the area “within hours.”

A Syrian state television reporter broadcast live from a part of Hanano on Saturday and said the Syrian army’s operation to secure the area was ongoing. Gunshots could be heard and behind him damaged buildings and rising smoke could be seen.

An official from Jabha Shamiya, one of the biggest groups fighting against Assad in northern Syria which has some fighters in Hanano, said there are back-and-forth battles and about half of Hanano has been taken by the government.

Rebels say much of Hanano has been empty of residents for some months.

Syrian state media said the army had secured the safe passage of at least 150 people out of Hanano, and showed pictures of people it said were evacuated residents in a reception center.

In the 12 days since the renewed bombardment on east Aleppo, at least 201 civilians, including 27 children have died in the besieged sector, the Observatory said. There were 134 rebel fighter deaths.

The monitor also documented 19 civilian deaths, including 11 children, and dozens of injuries as a result of rebel shelling of government-held west Aleppo. Rebel shelling into the Sheikh Maqsoud district, which is under the control of the Kurdish YPG militia, has killed three people, it said.

Syrian state news agency SANA said three people died and 15 were injured on Saturday when rebels fired rockets into government-held west Aleppo.