The U.S. Navy tweeted there are “several confirmed injured with reports of fatalities.”
The injured included a Washington, D.C., police officer who has been hospitalized, and another law officer not affiliated with the city force, said Metropolitan Police Department spokesman Chris Kelly.
The incident occurred at 8:20 a.m. when several shots were fired inside the headquarters for Naval Sea Systems Command in southeast Washington, D.C. An “active shooter” remained inside the building, the Navy said.
Kelly described the suspect as an adult black male, about six feet tall with a bald head and medium complexion, dressed in a black top and black jeans.
Emergency personnel, the FBI, U.S. Capitol Police and local D.C. police responded to the shooting, shutting down traffic in the area on the district’s south side along the Anacostia River. Some people are being evacuated and others are sheltering in place.
Air traffic to Reagan National Airport in northern Virginia, the closest airport to downtown Washington, D.C., was suspended,the Federal Aviation Administration said. There was no immediate confirmation the halt in incoming flights was due to the shooting situation.
A White House statement said President Barack Obama has been briefed on the situation.
The headquarters — the workplace for about 3,000 people — is the largest of the Navy’s five system commands. It has a fiscal year budget of nearly $30 billion.
“With a force of 60,000 civilian, military and contract support personnel, NAVSEA engineers, builds, buys and maintains the Navy’s ships and submarines and their combat systems,” the Navy said.
CNN’s Dan Merica, Barbara Starr, Paul Courson and Evan Perez contributed to this report.