The suspects held up the bus with the driver and two passengers who were travelling to work.
Fortunately, Police chief inspector David Terry was passing through when he happened on the scene.
“This incident happened as we were passing them near the Morata vocational centre,” Terry posted on his Facebook page.
“I was going to drop my nephew at Morata Three when the criminals struck.
“My friend who was driving my vehicle stopped in the middle of the road when we saw the thugs attacking the victims inside the bus.