At least 18 people were killed after a gunman went on a shooting spree in northeastern state.

A manhunt for Robert Card had been underway since 18 people were shot dead and 13 others wounded in Lewiston, Maine on Wednesday night.

Card, a sergeant at a US Army Reserve base, is believed to have died of a self-inflicted gunshot wound, multiple media outlets said, citing law enforcement officials.

The discovery brings to an end a 48-hour manhunt that followed the deadliest shooting in the modern history of Maine, a sparsely populated state located in the New England region of the northeastern United States.

Law enforcement officials earlier said that Card, 40, had a history of mental illness and was committed to a psychiatric facility for two weeks earlier this year.