According to the article:
Around 10:30 a.m., a security guard noticed a man walking into the bank wearing a trench coat and walking in a "stilted manner."
The man entered the bank lobby and produced a long gun from under his coat.
The two security guards on staff ordered the man to drop the weapon and drew their weapons on the gunman, police said.
When the gunman aimed at a security officer, the officer shot and killed him.
What isn't mentioned is that the same man is believed to have robbed this same Chase Bank branch twice in the last year and that the branch has been targeted four times in the last two years.
It seems Flint, Michigan has a bank robbery problem to add to all of it's other problems. If the bank realizes the best answer to armed robbers is armed guards, why doesn't the American public?