A man entered a Washington Mutual bank Monday morning and stole $1,000 cash, police say.

According to authorities, the robber entered the bank, located on Southern Boulevard and Westchester Avenue, at around 9:30 a.m. He took $1,000 cash and then fled by hopping on the downtown 5 train, which runs directly over the bank.

Police are unsure if the robber had a gun, or if he simply handed the teller a note. A teller who was in the bank at the time of the robbery says she?s seen the suspect before.