Egyptian and Libyan aircraft on Monday hit suspected Islamic State positions in Derna in Libya, reportedly killing at least 50 militants as well as several civilians.
According to the Human Rights Watch, a resident in the area said that the airstrikes also killed six civilians.
The unnamed resident told HRW that military aircraft began attacking positions in Derna around 6am, focusing particularly on the Aljabel Company compound, which hosted police officials tied to the Islamist group, and the al Shayha residential area. The Derna resident said that the attacks resulted in six civilian casualties, including three children and their mother.
Middle East and North Africa director for HRW Sarah Leah Whitson said that while ISIS showed excessive brutality in executing the hostages, any military action in response should be planned with civilian safety in mind.
"ISIS is again horrifying the world by perpetrating war crimes, this time showing no mercy in Libya," Whitson said. "But any military engagement with ISIS should take all possible steps to spare civilian lives."
HRW urged the United Nations to "establish an international investigative mechanism" to look into war crimes and the killing of civilians. The group also called on the International Criminal Court to investigate the incident with the UN and the governments of Libya and Egypt.
On Sunday, elements in Libya affiliated with the Islamic State published a video of the execution of 21 male Egyptian Coptic Christians. The men had travelled to Derna in Libya to find employment but were kidnapped by jihadists loyal to the ISIS between December and January.
On Monday, Egypt announced that it had launched retaliatory airstrikes on Islamic State weapons depots and training camps.
HRW reported that the Libyan government also launched airstrikes on Monday in Derna in coordination with the Egyptian military.
