BEIRUT (AP) — Syrian government warplanes and helicopter gunships launched new airstrikes Saturday on insurgent-held neighborhoods in the northern city of Aleppo. The fresh violence comes as the International Committee of the Red Cross warned that the intensification of fighting brings millions of people closer to a humanitarian disaster.

Contested Aleppo, Syria's largest city and former commercial center, has been the scene of intense shelling and air raids over the past nine days that killed nearly 250 civilians according to the Britain-based Syrian Observatory for Human Rights.

The surge in fighting has caused the collapse of a two-month cease-fire brokered by the U.S. and Russia. It also has raised fears of an all-out government assault on Aleppo and warnings of a humanitarian disaster in the 5-year-old civil war.

The ICRC statement issued late Friday said four medical facilities on both sides of the city were hit earlier that day, including a dialysis center and a cardiac hospital. ICRC appealed to all parties in the conflict "for an immediate halt in the attacks."

"There can be no justification for these appalling acts of violence deliberately targeting hospitals and clinics, which are strictly prohibited under international humanitarian law," said Marianne Gasser, head of the ICRC in Syria. "People keep dying in these attacks. There is no safe place anymore in Aleppo."

"For the sake of people in Aleppo, we call for all to stop this indiscriminate violence," Gasser said.

Friday's attacks on the medical centers came after government airstrikes damaged a main hospital supported by Doctors Without Borders late Wednesday, killing more than 50 people, according to the international aid group.

The ICRC said it has warned that because of the intensification of fighting in recent days, millions of people "are facing humanitarian disaster as it becomes increasingly difficult to reach them with aid."

Syrian opposition activists said Saturday's airstrikes on Aleppo killed four people and wounded many others, mostly in the neighborhood of Bab al-Nairab.

The Observatory and the Local Coordination Committees reported more than 20 separate air raids on rebel-held parts of the city where an estimated 250,000 people remain.

Aleppo-based activist Bahaa al-Halaby said warplanes and helicopter gunships are launching very "intense bombardments."

Another activist in the city, who spoke on condition of anonymity for his own safety, said schools have been ordered closed in rebel-held parts of Aleppo.

Aleppo was excluded from a brief truce declared by the Syrian army on Friday. The truce went into effect after midnight Saturday in the capital Damascus and its suburbs as well as the coastal province of Latakia. Activists said both areas included in the truce were relatively calm on Saturday.

In Damascus, ICRC spokesman Pawel Krzysiek said that despite the difficult situation in Aleppo that affects humanitarian operations in the city, the work elsewhere continued.

Two humanitarian convoys are on the way to two separate areas besieged by rebels and government forces respectively, he said.

The convoys, a joint operation between the ICRC, United Nations and the Syrian Arab Red Crescent, will deliver aid to Madaya and Zabadani — two mountain resorts near Damascus that have been besieged by government forces.

Krzysiek added that 20 other trucks are on their way to the northwestern villages of Fua and Kfarya, which are being besieged by insurgents.

The ICRC delivers food parcels and wheat flour, medicines, bed nets, crutches and anti-lice shampoo to all locations, he said.

Also Saturday, the U.N. Office for the Coordination of Humanitarian Affairs posted on its Twitter account that the aid delivery in the four areas will be large enough to serve 61,000 people.