BROOKLYN - The FBI has joined the search for a man who threatened to blow himself up inside an East Flatbush bank. 

According to investigators, the suspect walked into a Chase bank on Nostrand Avenue while holding what appeared to be a remote detonator. It happened just before 5 p.m. Monday. 

Police released surveillance video from inside the bank as they say the man showed a teller a note demanding cash and claiming that he would set off explosives. 

The man is described as being between 30 and 40 years old, and about 6 feet tall. He was wearing a white baseball hat, a dark denim jacket, glasses and white sneakers. 

A reward is being offered for any information leading to an arrest. If you can help, call the FBI tip line at 212-384-1000