A missile attack in southwestern Syria killed three journalists working for a network opposed to Bashar Assad's regime, the Committee to Protect Journalists (CPJ), said late Tuesday. The U.S.-based media advocacy group said that the attack happened Monday near the town of Sheikh Meskin, which is at the center of clashes between rebels and government forces.

CPJ cited the news network, Orient News, which claimed that forces loyal to Assad had carried out the attack on the journalists. The network identified the dead journalists as correspondents Rami Asmi and Yousef El-Dous, and cameraperson Salem Khalil. The three were reportedly travelling to cover the advances being made by the opposition forces, when their car was hit by a missile fired by government forces, according to CPJ, which added that it was unable to independently verify the claims.

Orient News and Siraj Press, another opposition news agency, reportedly said that the missile was launched from the town of Qarfa, which lies about two miles from Sheikh Meskin. 

"So many Syrian journalists have paid the ultimate price for reporting on this conflict, but even for Syria, the loss of three journalists in one attack is devastating," Sherif Mansour, CPJ’s Middle East and North Africa program coordinator, said, in a statement from the group, adding: "Journalists covering conflict are civilians and we call on Syrian authorities to respect that status."

According to CPJ, over 70 journalists, most of whom were locals, have been killed so far while covering the conflict in Syria, which began over three years ago, and has claimed the lives of hundreds of thousands of people and displaced millions.