It was probably a cow with glued on antlers

From The Evening Standard:

A woman has been treated in hospital after a deer ran loose in a city centre.

The wild animal was seen running down Chelmsford High Street on Sunday, knocking over pedestrians as it went. A woman in her 20s was taken to the Broomfield Hospital after suffering cuts and bruises when the deer attempted to jump over her.

A spokesman for the East of England Ambulance Service said: "We understand the deer, in its attempt to get away, barged into a number of people, sending some to the pavement. It also dazed itself when it hit a plate-glass window. The young woman was treated for minor facial injuries, then taken by us to Broomfield Hospital."

Essex Police said the deer was later spotted near the A12 dual carriageway. Roadblocks were set up to catch the animal but it was not seen again.