Live updates: Three police officers shot dead in Baton Rouge

The decorated ex-US marine sergeant who shot dead three police officers in Louisiana targeted them and assassinated them, authorities said on Monday.

One of three officers wounded by Gavin Long in Sunday's shootings was hospitalized and fighting for his life, police said at a news conference.

Detectives also released a photo showing three guns recovered from the shooting in Baton Rouge.

"There is no doubt whatsoever that these officers were intentionally targeted and assassinated," Louisiana State Police Superintendent Colonel Mike Edmonson said of the Sunday incident at the news conference.

"It was a calculated act against those who work to protect this community every single day." Edmonson said "the most compelling piece of evidence is the video."

Officers also revealed:

• They are examining Gavin Long's social media footprint
• Multiple pieces of evidence have been seized from the shooting scene
• Long had been in the city for several days

Revelations about the suspected Baton Rouge gunman Gavin Long are adding to rising political tensions in the US ahead of a divisive Republican party convention.

ITV News Washington Correspondent Robert Moore reports.

Hillary Clinton has vowed to bring the "full weight of the law" against people who kill police officers if elected the next president of the US.

The presumptive Democratic candidate was addressing the convention of the civil rights group the National Association for the Advancement of Colored People (NAACP) in Cincinnati.

Her comments follow the killing of three police officers by a gunman in Batton Rouge.

The NAACP also invited Donald Trump, the presumptive Republic challenger to Ms Clinton, but he has reportedly declined to attend the conference, which clashes with the timing of the Republican Convention.

The gunman who shot three officers dead in Baton Rouge in an ambush attack was "certainly seeking out police" to kill, Louisiana state police have said.

The authorities in the US state confirmed the expected motive for Sunday morning's shooting as they continue their investigation.

Police said they have spoken to people who had contact with Gavin Long and appealed for others to come forward.

The decorated former US marine died in a shootout with police minutes after launching his attack.

• Baton Rouge killer's anger at police revealed in videos

Three officers killed by a gunman during a shooting in Baton Rouge, Louisiana, on Sunday have been named.

The trio were identified as Montrell Jackson, Matthew Gerald and Brad Garafola.

The gunman who killed three police officers and wounded a further three on Sunday in Baton Rouge was a former Marine Corp.

According to a US government official, the gunman, named as 29-year-old Gavin Long, had previously served with the American forces.