So that Rome should not pass the year without war, however, a minor foray was made into Umbria when reports kept arriving of raids on the countryside being made by armed bands from a certain cavern. The Romans entered the cavern with their standards, and in it numerous wounds were inflicted on them because of the darkness of the place, especially from stones that were hurled at them. Eventually, the other entrance to the cavern was discovered—it was open at both ends—and wood was heaped up at both orifices and set alight. As a consequence, up to two thousand armed men were killed inside the cave by the smoke and the heat when, eventually, they rushed straight into the flames in their efforts to get out.

That "up to" is doing a lot of work there I think