The gunman who opened fire at the Capital Gazette newspaper in Maryland, killing five, barricaded the door to stop people from getting out and was bent on killing "as many people as he could kill," police and prosecutors said.
The mass shooting sent shockwaves through the journalism community and left investigators searching for answers.
"We can't fathom why this person chose to do this," Anne Arundel Police Chief Timothy Altomare said Friday, adding that he refused to say the name of the suspect.
Jarrod Ramos allegedly walked into the newspaper office at 888 Bestgate Road in Annapolis with a shotgun and fatally shot four journalists and a sales assistant Thursday afternoon.
Ramos had barricaded the back door, Anne Arundel County State's Attorney Wes Adams said.
"There was one victim that had attempted to escape through the back door and was shot," he said.
Keith Cyphers, who works in an office across the hall from the Capital Gazette, told "Good Morning America" he heard an "incredibly loud noise ... I could feel it in my chest."
Cyphers peered out from his desk and saw the Capital Gazette's door "shattered."
"There was a man who was holding a shotgun," he said. "He had it braced against his chest and he was moving through the lobby of the Capital Gazette office, pointing the shotgun deeper into the office."
Phil Davis, a crime and courts reporter with the Capital Gazette, tweeted, "There is nothing more terrifying than hearing multiple people get shot while you're under your desk and then hear the gunman reload."
"I thought we were going to die," Anthony Messenger, an intern at the Capital Gazette, told ABC News.
The alleged shooter tried to hide under a desk until police quickly responded and took him into custody, according to court documents.
The suspect's shotgun was legally purchased about one year ago, police said.
Ramos has not cooperated with authorities, police said. But evidence at his home indicated planning, police added.
President Donald Trump -- who has called the media "the enemy of the American People" -- said Friday "journalists, like all Americans, should be free from the fear of being violently attacked while doing their job."
"This attack shocked the conscience of our nation and filled our hearts with grief," Trump said. "My government will not rest until we have done everything in our power to reduce violent crime and to protect innocent life."
The five victims who died were employees of the Capital Gazette, authorities said.
Wendi Winters, 65, was a writer who worked for special publications.
Robert Hiaasen, 59, was the assistant editor for news and a columnist at the paper whose brother is author and journalist Carl Hiaasen.
Gerald Fischman, 61, was an editorial page editor and regularly wrote opinion pieces for the paper.
John McNamara, 56, was a staff writer.
Rebecca Smith, 34, the youngest victim, worked as a sales assistant for the paper.
Two other people were injured, though not wounded, in the shooting, and have been released from the hospital, authorities said.
"The Capital Gazette is my hometown paper, and I have the greatest respect for the fine journalists, and all the men and women, who work there," Maryland Gov. Larry Hogan said in a statement. "They serve each day to shine light on the world around us so that we might see with more clarity and greater understanding."
Hogan has ordered Maryland flags to be lowered to half-staff.
'We are putting out a damn paper'
Reporters and editors at the Capital Gazette vowed to publish a paper even after the death of their five colleagues. Through their grief, they worked alongside reporters from The Baltimore Sun, which owns the newspaper.
"There will be a Capital Friday," tweeted Capital Gazette photojournalist Joshua McKerrow.
"We are putting out a damn paper," reporter Chase Cook added.
The paper arrived on doorsteps and at convenience stores, as promised, with a headline reading, "5 shot dead at The Capital."
The suspected gunman and his history with the paper
Ramos is charged with five counts of first-degree murder and has been held without bail.
The native of Laurel, Maryland, about 30 minutes inland from Annapolis, apparently had a longstanding grudge against the local newspaper.
Tom Marquardt, the former editor and publisher of the Capital Gazette, told ABC News he first "crossed paths" with Ramos in 2012 when the newspaper wrote a story about the now alleged suspect in connection with a stalking case.
"Our court reporter had written about a case he had in which he was a defendant in a stalking case and he was, Jarrod was, quite upset with the story and he really created a webpage that allowed him to vent and express his frustration and his anger towards me, the reporter and the newspaper," Marquardt said. "Shortly after that, he filed a defamation lawsuit against us."
The lawsuit was the beginning of an ongoing campaign of hatred directed toward the Capital Gazette, Marquardt said.
"He represented himself and took advantage of the legal system to keep the case alive for a long period of time during which he sued lawyers, judges, anybody who crossed his path and disagreed with him," he said.
"During that time he continued to rant on his Facebook page to a point that we were feeling threatened physically from what he was saying. So during that time, we had consulted with our own lawyers in the best steps that we could take, as well as the police, and we had actually contacted the police to pursue one particular comment in which he wished I would be dead and the police looked into it."
Ramos' legal action against the newspaper was unsuccessful, Marquardt said, and the suspect exhausted all his appeals by 2014.
Marquardt said he could only comment on threats made against himself, but knew Ramos had wished him dead in the past on social media.
"We contacted police ... and they went out to talk to him," he said. "They reviewed all the tweets so far and again came away with the feeling that there really wasn't enough substance there to pursue a case in court."
Police said "online threatening comments were made in May 2013."
"The Capital Gazette did not wish to pursue criminal charges," police said Friday. "There was a fear that doing so would exacerbate an already flammable situation."