Officials confirmed one suspected shooter was in custody after the attack. Authorities have not named the suspect, did not say what type of gun was used or describe a possible motive.
The ATF and Federal Bureau of Investigation said they are also responding to a shooting at that location.
A shooting at a local newspaper in Maryland has left five people dead and more injured, say officials.
Phil Davis, a Gazette crime reporter who was there at the time of the shooting, said that multiple people had been shot.
In a series of tweets, Davis later wrote that a "single shooter shot multiple people", inside the office, "some of whom are dead".
Authorities said law enforcement were on scene within 60 seconds of the first report.
Walgreens tops profit estimates, authorizes share buyback
Fluctuations within the RSI can be dramatic at times, so it is not always an accurate measure of what a stock may be doing. If volume is decreasing in an uptrend, it could signal that the uptrend is coming to a close and a reversal may be likely.
Anne Arundel County Police spokesman Ryan Frashure said that officers arrived within about a minute of when they were alerted to the incident, and did not exchange gunfire with the suspect before taking him into custody.
Police respond to a shooting at the offices of the Capital Gazette, a daily newspaper, in Annapolis, Maryland, June 28, 2018.
Photojournalist Joshua McKerrow, who works for The Baltimore Sun and the Gazette, posted photos from the scene outside the building of law enforcement presence.
The Capital Gazette, located south of Baltimore, serves Anne Arundel County, Annapolis and Kent Island.
The City of Annapolis Office of Emergency Management tweeted at 2:42 p.m. CT that the Bestgate Road building had been evacuated. "But as much as I'm going to try to articulate how traumatizing it is to be hiding under your desk, you don't know until you're there and you feel helpless".
US President Donald Trump said on Twitter that he had been briefed on the shooting.
Maryland governor Larry Hogan tweeted he was "absolutely devastated" by events at the Capital Gazette's newsroom. "Praying for those at the scene and for our community".