A man is fighting for life after a dramatic fall from a Sydney shopping centre while allegedly trying to flee a store without paying.

The 29-year-old entered a store in Westfield Sydney on the corner of Pitt and Market Streets in the city’s CBD about 4.25pm on Thursday and tried on a pair of shoes.

Police say he then ran from the store without paying, prompting a staff member to give chase.

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The pursuit continued into a nearby shopping mall, where the man jumped a railing and plunged about six metres.

He was treated at the scene by paramedics before being rushed to hospital with a serious head injury.

A witness said the man landed face down, nearly hitting a woman who was walking by.

Footage from the scene showed the man surrounded by a pool of blood, with store tags and a security pin still attached to his shoes and clothing.

Despite his injuries, he kept trying to stand.

Bystanders attempted to calm him down, with one man holding him to the ground until help arrived.

As of Friday, the man remains in a critical condition.

The incident prompted the closure of Westfield Sydney on Thursday afternoon.

Police are continuing to investigate and have urged any witnesses to come forward.