Beware- New Bank Scam

My niece's Experience With An Unarmed Robber in a Banking Hall on July 10, 2015. I gave my niece who assists me at the shop to deposit 20K sales made into my GT bank account at Anthony Branch. She was in the banking hall- GT Bank branch, Anthony when she walked in with the money in her bag.
When filling her teller, someone asked her if she was paying in and she said yes. She later joined the long queue. After thirty seconds, a young man dressed in corporate suit (pretending to be a cashier) came close to her and asked for people who are paying . About five people stepped out and followed him a few meters away. He collected their money and teller and asked them to wait on the line so he can go in and stamp their teller at the cashier stand... Like play like play, the man left. They were waiting not knowing that he had left the banking hall with their funds It was later that they reported, the bank manager even came down.......he checked the cctv footage and behold, the gentle man in suit was neither a cashier nor a worker in the bank. Just like that, he stole their monies. The security guard was interrogated...my friends, pls BEWARE!!!