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The Associated Press
Abu Mohammed al-Golani, the leader of Fatah al-Sham Front, center, is seen in this picture posted by the group, discussing battlefield details with field commanders over a map. An alliance of insurgent groups, known as Army of Conquest and includes al-Qaida-linked Fatah al-Sham Front, said they have advanced into a district in al-Hamadaniyeh, Aleppo, Syria on Sunday, Oct. 30, 2016. Videos posted by the Fatah al-Sham group showed insurgents advancing into the neighborhood in tanks and other military vehicles. Writing in bottom at reads in Arabic: Sheik Abu Mohammed al-Golani inspects military development and discusses them with military commanders as part of the battle for lifting the siege off Aleppo. (Militant UGC via AP)

DAMASCUS, Syria — At least seven people were killed, including three children, and several others wounded, as the death toll climbed in insurgent shelling of government-controlled western districts of Aleppo, state TV reported Sunday.

The opposition monitoring group the Britain-based Syrian Observatory for Human Rights, which has a network of activists inside Syria, said at least 38 civilians, including 14 children, were killed since insurgents launched their offensive on government-held western Aleppo Friday. The state TV report said the civilians were killed in four districts.

Sunday's shelling came on the third day of the insurgent offensive that aims to breach a government siege on Aleppo's rebel-held eastern districts. A tight siege has been in place since July.

State media claimed that insurgent groups on Sunday used toxic gas to shell al-Hamadaniyeh, a neighborhood on the front lines of the battle.

The Syrian state news agency SANA said 35 people were treated for breathing difficulties. State TV showed residents and medics wearing masks rushing people into a hospital. At one point, a resident yells at the camera: "We don't any more truce. We want it to be settled militarily, no more truces."

The claim could not be independently verified. The government has made similar claims in the past.

Russia and the Syrian government have halted their airstrikes on the eastern rebel-held part of Aleppo since last week to allow for evacuation of wounded and civilians. But no evacuation took place and efforts to allow medical and food supplies into the besieged area also faltered. Pro-government troops have kept up a ground offensive.

Imad al-Khal, a 63-year old resident of western Aleppo, said there was fierce shelling over the past three days. "We are hearing now strong shelling by military jets and the artillery," he added.

Insurgent fighters have advanced on the district of al-Assad, capturing it Saturday and opened another front further north. Al-Assad district abuts the military academy, one of the government's major installations in the city.

It is at the western tip of al-Hamadaniyeh, which is the frontline between government-held Aleppo and the rebel-held part of the city.

An alliance of insurgent groups, known as Army of Conquest and includes al-Qaida-linked Fatah al-Sham Front, said they advanced into a district in al-Hamadaniyeh on Sunday. Videos posted by the Fatah al-Sham group showed insurgents advancing into the neighborhood in tanks and other military vehicles. The group's leader, Abu Mohammed al-Golani, appeared in pictures discussing battlefield details with field commanders over a map.

Residents reported heavy shelling. A state TV presenter, Shadi Halwi, said in a video post on his Facebook page that for the first time in government-held Aleppo, "the sound of clashes is strong, very loud."

Opposition fighters and the government have exchanged accusations of using chemical attacks on their respective areas.

An international team has determined that the Syrian government carried out a chemical attack in 2015, the third to be blamed on the government. An August report also blamed Islamic State militants of another chemical attack in 2015. IS is not part of the insurgent offensive on western Aleppo.

On Sunday, a Syrian military official, speaking on condition of anonymity in line with regulations, said the government is reinforcing its positions in and around the city to repel rebel advances.

The Observatory director Rami Abdurrahman said about 1,000 government artillery troops arrived in Aleppo from central Syria Saturday to take part in the counteroffensive. He estimated between 2,000 and 2,500 insurgent fighters are taking part in the offensive.

Associated Press writer Sarah El Deeb in Beirut contributed to this report.