SYDNEY (AP) — Australia today mourned the deaths of five of its soldiers in Afghanistan, three killed by an Afghan army colleague, in the nation’s deadliest hours of combat since the Vietnam War.

The Australians were killed in two separate incidents just hours apart late Wednesday and early today.

The first incident took place at a base in Uruzgan province, when a man in an Afghan army uniform opened fire on Australian soldiers, killing three and wounding two, according to Air Marshal Mark Binskin, vice chief of the Australian Defense Force. Hours later, two Australian soldiers died and a crew member was wounded when their helicopter rolled over while landing in Helmand province.

“In a war of so many losses, this is our single worst day in Afghanistan,” Prime Minister Julia Gillard said. “Indeed, I believe this is the most losses in combat since the days of the Vietnam War and the Battle of Long Tan. This is news so truly shocking that it’s going to feel for many Australians like a physical blow.”