BEIRUT — Airstrikes destroyed a hospital in northern Syria on Monday, leaving eight staff members missing, according to Doctors Without Borders, the international medical charity that supports the facility, one of three hospitals that were destroyed by warplanes in a single day.

The charity said the hospital, in the town of Maarat al-Noaman, was hit by missiles at least four times, with at least two sets of attacks coming within a few minutes of each other, a precise operation. Both Russian and Syrian warplanes operate over the area, in the insurgent-held Idlib province. Residents said that at least two nurses were killed and that five nurses and a doctor were missing in the rubble.

It was the second time in a week that a hospital working with the charity was hit. The charity said an affiliated hospital was bombed in Dara'a Province in southern Syria on Feb. 9.

"This appears to be a deliberate attack on a health structure, and we condemn this attack in the strongest possible terms," Massimiliano Rebaudengo, the Doctors Without Borders head of mission, said of Monday's strike on its affiliate. Deliberate attacks on medical facilities are forbidden under international law.

The hospital had 30 beds, 54 staff members, two operating rooms, clinics and an emergency room, and its destruction leaves 40,000 people without medical care, the charity said.

Antigovernment activists and residents said that warplanes had also attacked two other hospitals Monday. Three people were killed and six wounded in one, the National Hospital, which is also in Maarat al-Noaman. And in Azaz, a major prize in the fierce battles unfolding in Aleppo Province, a third hospital was hit by what residents and the Turkish government said was a ballistic missile.

Russian officials have said their country's airstrikes do not target civilians and have not killed any, though the United States and allied insurgent groups say that Moscow has bombed indiscriminately.

Syrian antigovernment monitoring groups say that Russian strikes have been the largest single cause of deaths in the war this year, and that they have killed hundreds of civilians, hitting schools, medical facilities and residential areas.

The strike came amid days of escalation along the Syria-Turkey border, despite the United States and Russia having agreed Thursday to work for a cease-fire, said to be starting by the end of this week.

Also Monday, residents of Azaz, in northern Aleppo, reported that a hospital there was struck by what some described as ballistic missiles. Turkish officials blamed Russia.

Azaz is one of the most complex theaters of the war in Syria, with combatants from many sides of the war clashing, sometimes with putative allies. Turkey has fired artillery into Syria, saying it is aiming at Kurdish-led forces that have taken territory from Turkish-backed fighters.

Doctors Without Borders has found its hospitals increasingly coming under fire in conflict zones. U.S. airstrikes killed 42 people at an affiliated hospital in Kunduz, Afghanistan, last year. The charity's hospitals have also been hit in a Saudi air campaign in Yemen.