Witnesses have described the "chaotic" and "scary" moment shoppers were injured in a stampede at a Sydney mall.

Five people were taken to hospital after being hurt in the crush,at Westfield Parramatta (9News)

Five people were taken to hospital after being hurt in the crush, when balloons containing what's thought to be vouchers and coupons for as little as $5 were dropped from the ceiling at Westfield in Parramatta at midnight.

Another 12 people were treated at the scene, with shopping centre staff among those scrambling to help.

Witnesses described chaotic and scary scenes. (Nine)

After the cascade of balloons was released, footage shows people thrown to the ground and pushed into a nearby area where families were meeting Santa.

Santa himself is sent flying, with screams for help heard in the furore.

One woman said people were being pulled out from broken pieces of the Christmas grotto, which then became a makeshift triage centre.

Ambulance crews were called to the shopping mall after midnight (Nine)

"The volume of the customers was nothing I have seen before," she said.

"As the balloons started to drop customers just started pushing in, and people were pushing against the set and it just pulled apart.

"The staff were literally pulling people in over the broken pieces and trying to administer first aid before paramedics came."

Santa's chair was used to treat injured shoppers (Nine)

She said the whole area was "just full of people who were injured."

Another witness, Vienne Baez described "chaotic scenes" and "lots of screaming".

"It was pretty crazy," she said.

The balloons contained vouchers for Westfield Parramatta. (Nine)

"It was a big, big crowd. Young people, old people.

"I think there were small vouchers, I don't know exactly what, I don't think it was a massive amount."

"It was probably $5 or $10."

A NSW Police spokeswoman said customers "were at that location to grab balloons as they were released and apparently the balloons had small gifts inside."

NSW Ambulance Inspector Phil Templeman said people suffered various injuries.

"Three of the transported patients had more serious issues including traumatic chest injuries, neck and back pain as well as nausea and dizziness," Insp. Templeman said in a statement.

He said it was "incredibly lucky" that no one was more seriously injured.

"As we go into the busy holiday period and many of our shopping centres become crowded with people, we urged the community to be patient and ensure the safety of themselves and those around them," he said.

Shoppers were crushed in the frenzy. (9News)

In a statement, a spokesperson for shopping centre bosses Scentre Group said customer's safety is their "priority".

"Our team acted swiftly to support our customers, contact emergency services and make the area safe," the statement said.

"Our team are continuing to speak with affected customers directly.

"We will continue to look into the circumstances surrounding last night's incident."