Airstrikes hit a hospital in northern Syria Monday, leaving behind seven dead and more than eight missing persons, according to Doctors Without Borders, who manages the hospital located in Maarat al-Moaman.

As first reported by the New York Times, no one has yet claimed responsibility for the attack, but both Russian and Syrian planes are known to operate in the area where it took place.

A second hospital in Maarat al-Noaman was also hit by airstrikes on Monday, killing three and wounding six. Additionally, two more hospitals and a school building housing displayed persons were also hit by airstrikes on Monday in Azaz, killing a total of 15 people. It is not yet known if these attacks were connected in any capacity.

According to Reuters, at least two of the casualties in Azaz were children.

UPDATE #Syria: At least 7 killed & 8 missing in the MSF-supported hospital attack in #Idlib https://t.co/FXTjNmAw8h pic.twitter.com/8IZREgifvE — MSF International (@MSF) February 15, 2016

In total, the New York Times reports that four Syrian hospitals have been struck by warplanes in a single day, and it is also the second time in the same week that a hospital working with Doctors Without Borders was targeted in an attack. Targeted attacks on medical facilities are prohibited under international law.