A number of people are feared to have been killed in a horror mass shooting at Sydney's Bondi Beach, 9News understands.

Vision from the scene shows two men opening fire from a bridge this evening, shortly before 7pm (AEDT).

Ten people are believed to have been shot.

LIVE UPDATES: People told to take shelter as police respond to reports of shooting in Bondi

9News understands one of the shooters has been arrested, while the other has been shot. 

Police issued an alert just before 7pm, urging the public to avoid the area due to the "developing incident".

"Anyone at the scene should take shelter," NSW Police said.

"Police are on scene and more information will be provided when it comes to hand."

The prime minister has issued a statement about the incident.

"We are aware of an active security situation in Bondi," a spokesperson for Prime Minister Anthony Albanese said.

"We urge people in the vicinity to follow information from NSW Police."

More to come.