A 48-hour manhunt was launched for Robert Card, 40, after a shooting at the Just-In-Time bowling alley and Schemengees Bar and Grille in Lewiston on Wednesday night.

Among those who were killed included Joshua Seal, a father-of-four, who was described by his wife as the "world's best father", and Bill and Aaron Young, a father and his 14-year-old son.

Maine shooting - latest: Suspected gunman Robert Card found dead

A further 13 people were injured, in what was the worst mass shooting in the state of Maine's history.

The Androscoggin County sheriff's office confirmed Card's death in a post on social media, saying the suspect in the shooting "has been located and is deceased".

It is believed Card died from a self-inflicted gunshot wound, public safety commissioner Mike Sauschuck said at a late night news conference in Lewiston.

He said Card was found dead at around 7.45pm local time near the Androscoggin River in the Lisbon Falls area, which police were pictured searching on Friday.

The town of Lisbon is around a 15-20 minute drive from Lewiston, where the shooting took place.

Officials said a note addressed to Card's son was found at a home associated with the suspect on Thursday. His mobile phone and a gun were also found in a white Subaru that was identified as belonging to him.

The search for the former army reservist spread across multiple locations in the state and involved at least 80 FBI agents and Coast Guard personnel.

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Card was considered "armed and dangerous" with police advising the public not to approach him "under any circumstances".

The US Army said Card was a petroleum supply specialist and Sergeant First Class - typically a senior non-commissioned officer rank - in the reserve.

He enlisted in December 2002, it added, saying he had no prior combat deployments.

An internal police notice said Card had been committed to a mental health facility for two weeks this summer, saying he had reported hearing voices and had threatened to carry out a shooting at the military training base in Saco, Maine.

The note did not provide specific details about his treatment or condition.

During the intensive search for Card, authorities lifted a shelter-in-place order on Friday evening for people living in the area.

Governor of Maine, Janet Mills, said she is "breathing a sigh of relief" to know the suspect is "not a threat" to anyone any more.

She said law enforcement will continue to investigate "all the facts" in order to bring some closure to the families of the victims.

Meanwhile, President Joe Biden said he would do everything in his power to "end this gun violence epidemic".

In a statement, the US leader wrote: "This has been a tragic two days - not just for Lewiston, Maine, but for our entire country. Once again, an American community and American families have been devastated by gun violence."

He called on Republicans in Congress to fulfil their obligation to keep the American people safe.