Two girls, 14 and 15, were allegedly indecently assaulted by a man on a mobility scooter while they were engaged in promotional work at Westfield Hurstville.
Members of the public came to the assistance of the teenagers after the alleged incident on Sunday.
Police later arrested a man, 72, at a home in Hurstville.
Police said the girls were inside the centre about 6pm when they were approached by a man on a mobility scooter.
“The man allegedly indecently assaulted both girls before members of the public intervened,” a police spokesman said.
“He left the scene and police were alerted.
“Officers from St George Local Area Command attended, spoke to witnesses and viewed CCTV footage.”
Police arrested a man, 72, at a home in Hurstville and charged him with two counts of indecent assault.
He was given bail to appear at Sutherland Local Court on December 5.
Inquiries into the alleged incident are continuing and anyone with information is urged to come forward.