Photos: Lockdown at the Navy Yard

D.C. Police Chief Cathy Lanier speaking at a news conference near the Washington Navy Yard Thursday, July 2, 2015. (WTOP/Kristi King)

Police Chief Cathy Lanier says the response shows lessons learned from the shooting two years go. pic.twitter.com/E9RqqMjE1N
— mollenbeckWTOP (@mollenbeckWTOP) July 2, 2015

(WTOP/Kristi King)

ViceADM Dixon Smith sz Navy Yard remains under lockdown for final checks #WTOP pic.twitter.com/T4yhaBCLEG
— Kristi King (@kingWTOP) July 2, 2015

(WTOP/Kristi King)

Mayor Muriel Bowser says an employee reported that she may have heard gunfire at Navy Yard. After search, no evidence pic.twitter.com/c57bUtK0nb
— mollenbeckWTOP (@mollenbeckWTOP) July 2, 2015

(WTOP/Kristi King)

A large police presence is seen looking down M St. in Southeast Washington, Thursday, July 2, 2015, near the Washington Navy Yard campus. A lockdown was underway Thursday morning across the Washington Navy Yard campus after reports of shots fired, but a senior law enforcement official said those reports had not been confirmed. (AP Photo/Andrew Harnik)

A U.S. Park Police helicopter hovers overhead at the Washington Navy Yard campus in Washington, Thursday, July 2, 2015. A lockdown was underway Thursday morning across the Washington Navy Yard campus after reports of shots fired, but a senior law enforcement official said those reports had not been confirmed. (AP Photo/Andrew Harnik)

A police officer runs down M St. in Southeast Washington, Thursday, July 2, 2015, along the perimeter wall of the Washington Navy Yard. A lockdown was underway Thursday morning across the Washington Navy Yard campus after reports of shots fired, but a senior law enforcement official said those reports had not been confirmed. (AP Photo/Andrew Harnik)

Police officers walks along the perimeter wall of the Washington Navy Yard in Washington, Thursday, July 2, 2015. The Washington Navy Yard was on lockdown Thursday morning after reports of gunshots, but a senior federal law enforcement official says there has been no confirmed report of any shooting. (AP Photo/Andrew Harnik)

People watch out of a window at a large police presence along M St. in Southeast Washington, Thursday, July 2, 2015, near the Washington Navy Yard campus. The Washington Navy Yard was on lockdown Thursday morning after reports of gunshots, but a senior federal law enforcement official says there has been no confirmed report of any shooting. (AP Photo/Andrew Harnik)

An ATF (Bureau of Alcohol, Tobacco, Firearms and Explosives) police officer walks toward the Navy Yard in Washington, Thursday, July 2, 2015. The Washington Navy Yard was on lockdown Thursday morning after reports of gunshots, but a senior federal law enforcement official says there has been no confirmed report of any shooting. (AP Photo/Jacquelyn Martin)

A large police presence gathers along M St. in Southeast Washington, Thursday, July 2, 2015. The Washington Navy Yard was on lockdown Thursday morning after reports of gunshots, but a senior federal law enforcement official says there has been no confirmed report of any shooting. (AP Photo/Andrew Harnik)

Officials respond to an incident at Navy Yard Thursday, July 2, 2015. (WTOP/Jim Lavin)

Multiple agencies continue to monitor the situation at the Washington Navy Yard. (WTOP/Jim Lavin)

A police officer puts up police tape near the Navy Yard in Washington, Thursday, July 2, 2015. The Washington Navy Yard was on lockdown Thursday morning after reports of gunshots, but a senior federal law enforcement official says there has been no confirmed report of any shooting. (AP Photo/Jacquelyn Martin)

Police vehicles are seen near the Washington Navy Yard in Washington, Thursday, July 2, 2015. A lockdown is underway on the entire Washington Navy Yard campus after a report of shots fired. (AP Photo/Susan Walsh)

Troops move carrying guns walk at the Navy Yard in Washington, Thursday, July 2, 2015. A lockdown is underway on the entire Washington Navy Yard campus after a report of shots fired. (AP Photo/Jacquelyn Martin)

Soldiers guard at the Navy Barracks in Washington, Thursday, July 2, 2015. A lockdown is underway on the entire Washington Navy Yard campus after a report of shots fired. A federal official says there were reports of shots fired Thursday morning in the same building where a gunman killed a dozen workers in a rampage two years ago. The official, speaking on condition of anonymity because the official wasn't authorized to discuss details publicly, says there are no reports of injuries nor has a shooter been identified. (AP Photo/Jacquelyn Martin) — Soldiers guard at the Navy Barracks in Washington, Thursday, July 2, 2015. A lockdown is underway on the entire Washington Navy Yard campus after a report of shots fired. A federal official says there were reports of shots fired Thursday morning in the same building where a gunman killed a dozen workers in a rampage two years ago. The official, speaking on condition of anonymity because the official wasn’t authorized to discuss details publicly, says there are no reports of injuries nor has a shooter been identified. (AP Photo/Jacquelyn Martin)

Members of the media gather on the corner of M St. and 4th Street in Southeast Washington, Thursday, July 2, 2015, after an official said shots have been reported in a building on the Washington Navy Yard campus. (AP Photo/Andrew Harnik)

A police officer speaks on his phone as a large police presence gathers along M St. in Southeast Washington, Thursday, July 2, 2015, after an official said shots have been reported in a building on the Washington Navy Yard campus. (AP Photo/Andrew Harnik)

A police officer walks along the perimeter wall of the Washington Navy Yard in Washington, Thursday, July 2, 2015, after an official said shots have been reported in a building on the Washington Navy Yard campus. (AP Photo/Andrew Harnik)

A large police presence gathers along M St. in Southeast Washington, Thursday, July 2, 2015, after an official said shots have been reported in a building on the Washington Navy Yard campus. (AP Photo/Andrew Harnik)

A helicopter hovers overhead as a police officer stands on the corner of M St and 4th St. in Southeast Washington, Thursday, July 2, 2015, after an official said shots have been reported in a building on the Washington Navy Yard campus. (AP Photo/Andrew Harnik)

A large police presence gathers along M St. Southeast near the Navy Yard in Washington, Thursday, July 2, 2015, after an official said shots were reported in a building on the Washington Navy yard campus. (AP Photo/Andrew Harnik)

Navy Yard response includes multiple agencies. (WTOP/Kristi King)

Thursday, July 2, the Navy Yard is on lockdown, according to the Navy Yard office. Employees are sheltering in place. (WTOP/Jim Lavin)

The Navy Yard campus is on lockdown, police are responding. (WTOP/Jim Lavin)

Employees at the Navy Yard are sheltering in place. (WTOP/Jim Lavin)

Thursday, July 2, the Navy Yard is on lockdown, according to the Navy Yard office. Employees are sheltering in place. (WTOP/Jim Lavin)

Navy spokesman Petty Officer 1st Class Pedro Rodriguez says a lockdown is underway at the Navy Yard, the Associated Press reports.

(WTOP/Jim Lavin)

SCap at M #WTOP pic.twitter.com/X4edo9h59E
— Kristi King (@kingWTOP) July 2, 2015

(WTOP/Jim Lavin)

Navy confirms #navyyard on lockdown, with people sheltering in place. pic.twitter.com/1LJmSPEXzN
— Neal Augenstein (@AugensteinWTOP) July 2, 2015

(WTOP/Jim Lavin)

Lockdown at Washington #NavyYard pic.twitter.com/lb5Mf5FCYd
— Neal Augenstein (@AugensteinWTOP) July 2, 2015

(WTOP/Jim Lavin)

Large police presence along M St SE between S Capitol St & 11th St near Navy Yard. Updates from @WTOP @alex_prewitt pic.twitter.com/bhvMIyuU0c
— WTOP Traffic (@WTOPtraffic) July 2, 2015

(WTOP/Jim Lavin)