"It was quite apparent that this individual had some type of a vendetta against the Capital [Gazette] newspaper, and they were specifically targeted," an officer with Annapolis police told reporters at a briefing.
Police evacuated over 170 people from the building, which also housed many businesses, he added. Many of them are witnesses and are being interviewed by detectives. The officer said the probe was progressing swiftly and investigators would eventually "get to the bottom of it."
William Krampf, acting chief of police for Anne Arundel County in the US state of Maryland, said the Capital Gazette had received threats on social media before Thursday’s attack.
"What I can share with you now is that they were general threats towards the Capital media outlet," the officer told reporters, adding the messages "indicated violence."
Krampf said police had no knowledge that the gunman had targeted anyone specifically when he opened fire at the office. He also said he could not confirm at this time that all five fatalities were Gazette employees.
The Gazette cited law enforcement sources who said 38-year-old Jarrod Ramos was the shooter. The suspect filed a lawsuit against the newspaper in 2012 after it published a story in 2011 about a criminal harassment case against him.
The case against columnist Eric Hartley also featured Capital Gazette Communications and its former editor and publisher Thomas Marquardt as defendants, the paper reported.