LOS ANGELES, CA (Catholic Online) – According to the U.K.-based Syrian Observatory for Human Rights, the men killed were foreign fighters who had joined the insurgency but were caught trying to leave territory controlled by militants. These numbers were probably underestimates. "We believe that the real number of people that had been killed by ISIS is higher than the number documented," it said on its Web site.

Those who were killed for their attempted desertion were among at least 1,878 people executed in six months by the self-styled Islamic State, which enforces an extreme version of religious law on the areas it controls. The group says that of 930 of the civilians executed by ISIS were members of the Sheitaat. The Sheitaat is a Sunni Muslim tribe from eastern Syria, which fought Islamic State for control of two oilfields in August.

The Islamic State insurgency raging across Iraq and Syria has drawn many thousands of disaffected, young and radicalized Sunni Muslims. Many of them believe it is a chance to show their pious devotion while having the adventure of a lifetime.

Sunni youths in towns overrun by the insurgent group also face a deadly choice, between becoming fighters or suicide bombers for the group.

A 14-year-old handed himself in to Iraqi authorities after he was sent to blow himself up inside a Shia mosque last week.

Islamic State has become notorious for its brutality, releasing videos of executions of captured enemy fighters, activists and journalists.

About 116 foreign fighters, who had joined Islamic State but later wanted to return home, were executed in the Syrian provinces of Deir Al-Zor, Raqqa and Hassakeh since November. Four other Islamic State fighters were killed on other charges, according to the group