 What mission the 3rd Regiment had been performing near Ross remained a mystery, but the Americal Division obtained more evidence a week later that something was afoot.On the afternoon of 5 December, an air cavalry troop commander assigned to support the 3rd Brigade, 1st Cavalry Division, was training a new gunship team from the 1st Squadron, 9th Cavalry, when he spotted some people on a ridge north of LZ Ross.After the helicopters made a low pass that identified them as PAVN, the two gunships opened fire and cut down several of the figures.