Video image of an aquarium explosion in a Shanghai mall. (SCREENGRAB)

A 30-tonne aquarium with fish, turtles and sharks exploded suddenly in a Shanghai mall earlier this month, injuring more than a dozen people, international media report.

The explosion on Dec. 19, caught on closed-circuit television and posted to YouTube, sent shards of glass flying at unsuspecting shoppers when the seven-metre-long tank burst.

The video shows onlookers get swept up in waves as the water gushes out of the aquarium.

"There was no warning. Just a loud crack and it went. I've never been so scared," a worker at the Shanghai Orient Shopping Centre told the Austrian Times.

The glass was reportedly 15 cm thick.

Russia Today reports 15 people were injured, including eight shoppers and seven staffers.

"There were lots of injuries caused by flying glass, some of them serious because the glass was so thick. We are investigating what caused this," a police spokesman said.