An investigation is under way after a mother was left bleeding when she was struck by debris during Norwich's Big Boom fireworks display.
Samantha Colk, 36, was watching Friday's city centre display when she was hit by a 'golf ball'-sized piece of debris.
Event organiser Norwich City Council has apologised and launched an investigation.
While an exclusion zone was set up to stop the public going down part of London Street, Mrs Colk was not in the out-of-bounds area.
Mrs Colk, who lives in The Avenues in Norwich, had been standing close to the HSBC bank in London Street when she was struck, leaving her with a gash and blood pouring from her head.
Her husband Neil, 40, said: 'We had been watching the display for about eight minutes when something came down on my wife's head.
'I initially thought someone from behind us had thrown it.
'There was blood pouring from the top of her head. It was really frightening.
'I only got a glance at what hit her, but it looked like a golf ball sized piece of concrete'
Mrs Colk, who works in a pre-school, was checked by city council staff, but then had to make her way through the crowds to The Forum to be treated by ambulance staff.
Her injury did not require stitches, but her GP has told her to expect headaches for the next 10 days.
A spokeswoman for Norwich City Council said the exclusion zone had been extended following a safety meeting on Friday afternoon, because the wind direction had changed.
But the spokeswoman said: 'Despite this, during the Big Boom display a piece of compacted chalk from a firework hit a member of the public while she was stood just outside the exclusion zone. She was successfully treated at the scene.
'We're obviously very concerned that an incident like this could happen and we're deeply sorry that someone was injured at one of our events.'
She said the firework company has been asked to carry out an investigation.
The spokeswoman added: 'We've been working successfully with the same firework company for many years to host Big Boom and their safety track record has been spotless, so we await the findings of the report.'
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