“They were armed with pistols and an axe,” said Stockholm police spokesperson Towe Hägg to TT.
She said that there were several reports that someone had been wounded in the attack.
It is still unclear how much money the robbers managed to get away with.
The alarm was raised at around 3.45pm.
The robbers attacked the guards as they were on their way out from the store to the vehicle.
“One of them swung an axe at a security case,” said Hägg.
That case was left at the scene and police have not yet confirmed whether the robbers made off with another one.
After the raid, the three men fled in a dark jeep which was later found in the vicinity. It had been set on fire.
Later in the afternoon a second escape vehicle was found in Smedby, in Upplands Väsby. Police have now called for information from the public which will help them trace the robbers’ escape route.