Louisville, Kentucky - A gunman and five other people were shot and killed in an attack on a bank in the city of Louisville on Monday, police reported.

A further eight people, two of them police officers, were injured and are being treated in hospital, the report said.

Louisville deputy police chief Paul Humphrey said police were on the scene minutes after the emergency call came through. They exchanged fire with the gunman. During the exchange, the two officers were injured.

Humphrey said it was still not clear whether the gunman had been shot by police or had killed himself. According to the initial investigation, the gunman was a current or previous employee of the bank.

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Humphrey said rapid police action had prevented further loss of life.

President Joe Biden responded to the mass shooting via Twitter: "Once again, our nation mourns after a senseless act of gun violence – Jill and I pray for the lives lost and impacted by today's shooting. Too many Americans are paying for the price of inaction with their lives. When will Republicans in Congress act to protect our communities?"

Kentucky Governor Andy Beshear said two of those who died were his close friends, adding that a third friend was being treated at a hospital. Fighting back tears, he described the events as "awful."