Guttural Scream
A few of them had worked ahead of the others and made way for them to lay the gravel. While the group behind had been busy working, they suddenly heard some screaming.
An alert that something had shocked them into a frenzy. What would call for such a guttural scream? They hastily went to the rest of their colleagues to assist where necessary. Collectively their hearts dropped as they realized what they were seeing.