A series of airstrikes Monday killed dozens of people and injured many more in a Syrian coastal province, according to activists with the Syrian Observatory for Human Rights. Among the dead was a rebel commander who used to serve in the Syrian army under leader Bashar Assad.

The airstrikes began Monday and lasted for several hours, and have been described by the activists as some of the most deadly attacks since Russia began providing air support for Assad's forces in Syria at the end of September. The airstrikes have accompanied ground forces in the targeted regions, including troops from Assad's army as well as Lebanon's Hezbollah, a militant group that is also fighting in the civil war there. The exact number of deaths is not known, but activists have indicated that anywhere between 45 people and 57 people were killed, and the majority appeared to be from Russian attacks. 

The overall death toll from Russian attacks is climbing, those activists note. In the past three weeks, an estimated 370 people, including 127 civilians, have been killed as a result of Russian air attacks. A total of 243 rebel fighters were killed in the attacks, including members of the Islamic State and the Nusra Front, which is the al-Qaeda affiliate in the country. Of the dead civilians, 36 are said to have been children and 34 were women.

The civil war in Syria has had a devastating impact on local populations both in terms of deaths and quality of life. Since the conflict began in March 2011, it is estimated that half of the original population of 20 million has either fled the country or been displaced internally. There are a total of 4.2 million Syrian people who are registered as refugees, according to the United Nations Refugee Agency.

Russia's stated goal with airstrikes in the country is to help the Syrian government defeat so-called insurgent groups, including the Islamic State group and the Nusra Front. The Syrian government repeatedly refers to rebel groups in the country as "terrorists."