Illinois State Police say two people died and a third was critically injured during a bank robbery in the southern Illinois city of Cairo.

Investigators say a person of interest is in custody in connection with the First National Bank holdup shortly after 5 p.m. Thursday.

State police say a man entered the bank with a knife and a gun, though details have not been released.

No charges have been filed. A spokesman with the FBI's Springfield office says that agency is heading the investigation, and more details may become public later Friday.

The victims' names haven't been released. A relative told WSIL-TV that her cousin died in the robbery and says the family is "just in shock right now."

Both of those who died worked for the bank.