The gang set off explosives outside the warehouse belonging to cash courier company Loomis Sweden in Umestaden in Umeå but were unable to gain access to the premises.
Local police were quickly on the scene and started firing at the gang members, injuring one. He was taken to hospital and his injuries are not life-threatening.
“I can say that when the police arrived at the scene shots were exchanged in self defence during which a person sustained gun shot wounds,” said Carina Lundberg at Umeå police to news agency TT.
Lundberg confirmed that national police’s counter terrorism and organised crime unit had been called in to assist local police.
“We have also requested help from the National Investigation Department (Rikskrim), we need all the help we can get at the moment,” she said.
The commanding officer of the organized crime unit, Bertil Olofsson, was unwilling to comment on whether the plans to rob the facility were known to the police beforehand nor why the unit was already in place in Umeå.
“We arrested four of them and we have information that there are more people on the loose so we are continuing to chase them,” Olofsson told AFP at 2pm.
According to local newspaper Västerbottens Kuriren, three-four masked and armed police stopped a car in Sävar outside of Umeå and arrested the driver, although police were unwilling to confirm the details.
The police operation is ongoing, as they suspect that a large number of people may have been involved in the heist.
The robbers tried to blow their way into the Loomis securities register centre in Umestaden, Umeå at 9.20am on Sunday.
“They tried to blow up an entrance door, but did not manage to gain access to the premises. Our staff there are unhurt, but they are naturally shaken. It was quite an explosion,” said Stefan Wikman at Loomis Sverige AB to TT.
Wikman declined to reveal how much cash was being stored at the depot, but said he believed the gang struck on this date as Swedish salaries are set to be paid out overnight.
“It is natural that more cash is handled at this time because of (the forthcoming) payday,” he was quoted as saying.
As the alarm over the robbery was sounded a car exploded outside the garage at the main police station, but police managed to get out despite the disruption and could quickly make their way to Umestaden.
“It would appear that there is a link to the robbery,” said Carina Lundberg.
Police are continuing their investigation on Sunday afternoon and have appealed for information in their hunt for further possible suspects.