Undercover police teams from two Detroit precincts ended up fighting each-other instead of crime during a drug operation gone wrong.

Dozens of officers were involved in a mass brawl that saw punches thrown, weapons drawn and one cop sent to the hospital, Fox 2 Detroit reports.

Senior officers have now opened an investigation into the incident which is alleged to have happened on Thursday last week on the city's troubled east side.

Undercover officers were conducting a drug sting on Andover, a street in the notoriously drug-ridden east side of Detroit when they were approached by some more undercover cops

The encounter started when two special operations officers from the department's 12th Precinct were working on a drug bust on Andover, a notoriously drug-heavy area of the city.

The officers were pretending to be dealing narcotics in hopes that eager customers would approach before being arrested and having their vehicles seized.

But problems started when another group of undercover special operations officers from the 11th Precinct approached, posing as buyers.

When they showed up and started speaking, the 11th Precinct officers ordered the other cops to the ground - not realizing they were fellow boys in blue.

Officers from the city's 11th Precinct (pictured) ordered their colleagues from the 12th Precinct on to the ground without realizing who they were, it is reported

More cops from the 12th Precinct (pictured) then rolled in and started raiding a house before a fight broke out between the two groups, leaving one person in hospital

The rest the 12th Precinct's special ops team then showed up, and officers began raiding a drug house on the 19300 block of Andover.

But scenes quickly descended into a farce with the two teams of police fighting each-other as the stunned homeowner watched on.

Detroit Police Department's chief has been notified, and Internal Affairs is opening an investigation into the officers involved.

The incident is understood to have been captured on a body camera, with footage now part of the investigation. Police chiefs have refused to comment.