The man entered a Handelsbanken branch office on Monday and cut two workers before walking away.
“He has admitted that it was he who cut the two people,” said Christina Lycke Alhbin, police spokeswoman.
Police are hoping to get a clearer picture after more questioning. The 40-year-old was also drug tested, but results won’t be back for several days.
“What we know up to this point is that it was an assault and not an attempted robbery,” she said.
Two men, thought to be 45 to 50-years-old, were seriously injured in the attack and were taken to the hospital where their situation was described as serious but stable.
Police detained the man shortly after the attack. No money was taken from the bank.