A suspicious package investigation took an unexpected turn when a cyclist, apparently frustrated by the police's handling of the event, emptied the bag's contents onto the street. He was tackled to the ground by police immediately afterwards.
The bag was reported to police after it was spotted on top of an electrical box on Wisconsin Ave in downtown Milwaukee shortly before 7am.
The call prompted response from police and the bomb squad who were investigating the "suspicious package" before the bizarre scene unfolded.
The bag was moved from the box onto the road intersection by an official in protective armour as a safety precaution causing the road to be blocked off with police tape.
The seemingly impatient road user is seen getting off his bike next to the yellow tape before picking up the bag and tipping out the contents - which included water bottle, clothing and smaller items - onto the street.
The cyclist then slams the bag on the road before hastily being tackled to the ground by a number of officers, including FBI, with one of them cuffing the assailant.
The bomb squad and police remained at the scene after the man was taken into custody.
Eyewitnesses described how they feared the man was "going to get blown up" because of his reckless behaviour.
One said: "He rode past me and was saying, 'I'm going to defuse this situation,'
"I was concerned for everyone still around but really concerned for him. He was not acting in his right mind.
"If I would have saw him coming down the sidewalk earlier, I would have tried to stop him. It's a scary situation. You don't know if it's a bomb or backpack. When he went and did it, I thought oh no. It's not going to end well. It's going to end bad."
Milwaukee Police have not released any further information about the incident.