WARNING: RACIST ABUSE AND SWEARING IN THIS VIDEO
Travel bosses are investigating a shocking brawl which erupted on the top deck of a busy bus.
The near two-minute footage, uploaded to Facebook, showed two men wrestling on top of seats.
Punches were thrown before another passenger forced the pair apart and manhandled one of them to the bus floor.
A spokesman for bus operator National Express confirmed an investigation had been launched but refused to tell the Mail what time the fight had broken out.
"We are aware of an incident on board a 94 bus service, which we are currently investigating," the spokesman added.
The fight began after one passenger, dressed in a dark blue polo shirt with a light blue jumper around his neck, stood up to challenge another, wearing a baseball cap, and shouted: "Respect me like a man".
But tempers boiled over and racist language was used in the exchange.
A peacemaker tried to reason with the man dressed in blue, but then became a target as he was pushed against the bus window.
Other passengers on the packed bus, including women, stayed silent but were seen on camera running for cover as the violence began.
No comment was immediately available from West Midlands Police.
The latest annual Bus Satisfaction Survey, from commuter campaign group Passenger Focus, showed concerns about yob behaviour on the West Midlands' buses had fallen by seven per cent from 2012 to 2013.
Passengers using public transport in the region can instantly report troubling behaviour through the 'See Something, Say Something' mobile phone app.