A gunman fired through a glass door at a newspaper in the Maryland capital of Annapolis and sprayed the newsroom with bullets on Thursday, killing at least five people and injuring several others, news reports said.
Police confirmed five people had been killed in the shooting, while others are "gravely injured."
The suspect has been apprehended and no motive is known for the attack at the Capital Gazette newspaper, local news reports said. Law enforcement in Baltimore and New York City deployed protective forces to major media outlets as a precaution, authorities said.
For now, the Annapolis shooting is being treated as a local incident and not one that involves terrorism, a law enforcement official said. The Federal Bureau of Investigation is on the scene assisting local authorities, the official said.
A reporter for the Capital Gazette, Phil Davis, tweeted that a "gunman shot through the glass door to the office and opened fire on multiple employees." He said several people were killed.
"There is nothing more terrifying than hearing multiple people get shot while you're under your desk and then hear the gunman reload," Davis said.
The newspaper is located in a four-story office building in Annapolis, the capital of the U.S. state of Maryland.
U.S. President Donald Trump has been briefed on the shooting, White House spokeswoman Lindsay Walters said.
"Our thoughts and prayers are with all that are affected," she said. Trump was aboard Air Force One, returning to Washington from an event in Wisconsin.
One law enforcement source told CBS News the suspect is a male in his 20s who had no identification on him. Two law enforcement sources told CBS News the suspect used a shotgun.
Police also went to the offices of the Baltimore Sun as a precaution, that paper reported.
The New York Police Department said it was beefing up security at New York-based news organizations as a precaution.
"We're deploying units from our Critical Response Command to news outlets throughout New York City," said Officer Andrew Lava, an NYPD spokesman.
"There is no active threat at this time," he said.
Agents from the Baltimore office of the Bureau of Alcohol, Tobacco, Firearms and Explosives were responding to the incident, the bureau tweeted.
Police are checking the building in Annapolis for explosives and whether more than one suspect was involved, Anne Arundel County police spokesman, Lieutenant Ryan Frashure, told reporters.
Live video images showed people leaving the building, walking through a parking lot with their hands in the air. Scores of police vehicles were on the scene.
