Bertil Olofsson, head of Swedish national police's counter terrorism and organised crime unit said that arrests had been made although some of the robbers were still at large.
"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.
The injured man was taken to hospital where his condition was not said to be life threatening.
Stefan Wikman, an executive of Loomis security, which owns the depot, said that the staff inside were unharmed.
"Our staff there are unharmed, but they are obviously still in shock. It was a loud explosion."
Wikman did not 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.