A police department spokesperson said one of the 57 people injured appeared to be in critical condition.
"People were thrown into the air and onto the ground," passenger Elizabeth Banta told CNN. "There were definitely many people on the ground who were not moving."
More top news
An Ipsos MORI poll, commissioned by the League Against Cruel Sports (LACS), found 84% of the public do not want a return to fox hunting.
As Birmingham bids for the Commonwealth Games, we have been looking at sporting venues in the city which could be involved in the event.
Birmingham is bidding to host the 2026 Commonwealth Games, with those involved calling on the entire region to back it.