A US newspaper received threats on social media before five employees were killed during a "targeted" gun attack at their office in Maryland, police have revealed.

The shooting happened at The Capital Gazette in Annapolis at around 2.40pm local time on Thursday and a white male in his late-30s was arrested in connection with the incident shortly after.

US media reports that the suspect is 38-year-old Jarrod W Ramos, who is said to have had a history with the newspaper, but police have said not to expect any further update until Friday morning local time.

Image: Jarrod W Ramos is in custody according to US media reports

In a later news conference, acting police chief Bill Krampf said the gunman had used smoke grenades upon entering the building for their "targeted attack", and opened fire with what is believed to have been a shotgun or "long gun".

An official said the suspect was being interviewed by officers but has so far been uncooperative.


:: Victims of Capital Gazette newsroom shooting named

Police revealed that the newspaper had received threats via social media before the shooting and investigators are working to confirm any connection to the suspect, who they said had "prepared" for the attack.

Image: Police said they had arrived within 60 seconds of the shooting being reported

Mr Krampf said the hostile messages "indicated violence" and officers were "trying to confirm who actually sent them".

Among the victims was editor Rob Hiaasen, 59, a veteran journalist described by his brother Carl as "one of the most gentle and funny people I've ever known".

Trump refuses to comment on newspaper shootings

Paying tribute on Facebook, the Miami Herald columnist said: "I am devastated and heartsick to confirm the loss of my wonderful brother Rob today in the mass shooting in the newsroom at the Annapolis Capital Gazette.

"Rob was an editor and columnist at the paper, and one of the most gentle and funny people I've ever known.

"He spent his whole gifted career as a journalist, and he believed profoundly in the craft and mission of serving the public's right to know the news."

Image: Gazette editor Rob Hiaasen (left) and brother Carl. Pic: Facebook

Police confirmed the other victims as community news reporter Wendi Winters, sales assistant Rebecca Smith, editorial page editor Gerald Fischman, and staff writer John McNamara.

The Gazette's crime reporter Phil Davis wrote on Twitter in the aftermath of the attack that the gunman had "shot through the glass door to the office and opened fire on multiple employees".

"Can't say much more and don't want to declare anyone dead, but it's bad," he added, as he told his followers that the shooter had hit "multiple people at my office, some of whom are dead".

"There is nothing more terrifying than hearing multiple people get shot while you're under your desk and then hear the gunman reload," he said.

Image: Community news reporter Wendi Winters was one of the victims. Pic: The Capital Gazette

Mr Davis said he was tweeting after leaving the office and while waiting to be interviewed by police, who also found a suspected explosive device at the scene.

Spokesman Lt Ryan Frashure said it had been "taken care of" and police do not believe there were any others.

Mr Krampf added: "It's going to be quite a while determining what occurred, why it occurred and how it occurred.

"We do have fatalities and we do have serious injuries. We also have many, many witnesses being interviewed."

Image: Editorial page editor Gerald Fischman was one of the victims. Pic: The Capital Gazette

Police later confirmed that two other people had suffered "superficial" wounds during the shooting.

Despite the attack, the newspaper plans to release an edition as normal on Friday.

One of Mr Davis' colleagues, reporter Chase Cook, wrote on Twitter: "I can tell you this: We are putting out a damn paper tomorrow."

The incident prompted police in other states to take caution around other media outlets.

Image: A suspected explosive device was found after the building was searched

Officials in New York said: "We are monitoring the reports from Annapolis and have deployed counter-terrorism teams to media organisations around New York City.

"These deployments are not based on specific threat information, but rather a standard practice out of an abundance of caution."

Maryland governor Larry Hogan said he was "absolutely devastated to learn of this tragedy in Annapolis".

Congressman John Sarbanes, who represents the area, told Sky News that the newspaper had been part of the community "for decades and decades".

Image: The building is secure and a suspect is being interviewed by police

"They really feel the pulse of this community and now the community is going to feel the ripple effect from the newspaper itself," he said.

US president Donald Trump tweeted, offering "thoughts and prayers (for the) victims and their families", but refused to comment when questioned by reporters outside the White House.

His press secretary, Sarah Huckabee Sanders, said on Twitter: "Strongly condemn the evil act of senseless violence in Annapolis, MD.

"A violent attack on innocent journalists doing their job is an attack on every American. Our prayers are with the victims and their friends and families."