At least 117 civilians have been killed in the Syrian city of al-Raqqa since June 6, when US-backed Syrian forces began an offensive to expel the IS, a British-based war monitor reported.The Syrian Observatory for Human Rights said that the civilians, including 25 children and 21 women, lost their lives in fighting and airstrikes by the US-led international coalition, Efe news reported.The SOHR explained that the coalition's airstrikes also injured hundreds of citizens, with some of the victims suffering mutilation of limbs or permanent disability.It added that the death toll could rise due to the serious condition of those injured.Dozens of houses and civilian facilities in the Syrian city were destroyed because of the intense bombing against al-Raqqa city and its surroundings.The NGO added that the airstrikes and military operations of the Syrian Democratic Forces -- a Kurdish-led alliance backed by the US -- killed 142 IS militants, including local leaders.On Friday, the SDF announced it had killed 312 IS militants and captured seven others during the 10-day offensive in al-Raqqa.On June 6, the SDF started an offensive to retake the provincial capital of al-Raqqa, the Islamic State's main stronghold in Syria since it established its self-proclaimed "caliphate" in 2014.