7:53 a.m.

Alexis drives his rented Toyota Prius into Parking Garage No. 28.

8:08 a.m.

12Wearing a backpack, he enters Building 197 with a valid Common Access Card and takes an elevator to the fourth floor, where he worked. He enters a bathroom and emerges seven minutes later with a shotgun that he had purchased two days earlier.

Altered Remington 870 shotgun

8:16 a.m.

3Alexis shoots the first victim in the west side of the fourth floor, and the first 911 call is made immediately afterward. A four-person active-shooter team is assembled and reaches the Navy Yard in two minutes.

8:20 a.m.

4Alexis takes stairs down to the third floor and continues shooting.

8:23 a.m.

Seven minutes after the police received the call, the first units armed with AR-15 assault rifles hear shots and enter the building.

8:28 a.m.

5An e-mail goes out to Navy Yard workers telling them to “shelter in place.” Alexis arrives in the first-floor lobby. He kills a security guard and takes the guard's handgun, a 9mm semiautomatic Beretta. FBI Director James Comey said security video shows that Alexis appears to runs out of shells, drops the shotgun and begins firing with the handgun.

9mm Beretta

8:30 a.m.

Navy Capt. Christopher Mercer begins e-mailing his commanders from under his office desk to report that the shooter had been on the west side of the third floor.

8:57 a.m.

6Alexis returns to the third floor and continues shooting. The timeframe is unclear, but at some point, a man in an alley outside is hit by a stray bullet and Officer Scott Williams is wounded on the third floor. NCIS officers carry Williams down the stairs to safety.

9:25 a.m.

7After multiple encounters with law enforcement officers, Alexis is fatally shot in the head in a third-floor office.

Building 197 was built in 1939 as a factory that made guns for battleships during World War II. It has housed the Naval Sea Systems Command since 2001. Learn more about the Navy Yard.


Shooter enters building

Visitor entrance

Employee entrance
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One witness’s account

This is a condensed version of an account Navy Capt. Christopher Mercer gave to Post staff writer Aaron C. Davis.

Mercer said that minutes after shooting began on the fourth floor, Aaron Alexis arrived on the west side of the third floor and fired a gun across the hall, into the office of Michael Arnold.

Mercer and three aides meeting in his office slammed the door and pulled furniture in front before a bullet ripped through the door. The four dove under his desk.

Alexis kept shooting but never said a word, Mercer said. “He set up camp right in front of my office. He kept reloading and firing at cubicles.”

At one point, Mercer would later learn, Alexis walked through the aisles and pointed a shotgun at a young woman on his staff who was crouching beside a filing cabinet. Alexis pulled the trigger, but nothing happened.

Huddled under his desk, Mercer began firing e-mails to his boss who was standing outside, relaying the account to police commanders.

“The gunman was here,” Mercer wrote. “Is he still there?” his boss asked. “I can’t tell,” Mercer wrote. “We’re still barricaded in my office.”

Stay there, they were told.

After more than 20 minutes of quiet, the gunman returned.

“He was next door, through a little gypsum wall. He was moving furniture,” Mercer said. Mercer knew the office number and e-mailed the coordinates.

Within minutes he could hear police, and then an eruption of gunfire.

“It was a fierce, major gun battle,” Mercer said. “Bullets were flying through my office, over our heads, and kept going for minutes. Then, I heard, ‘Shooter down. Shooter down.’ ”



Assembles gun in fourth-floor bathroom


Shoots on Floors 4 and 3


Shooter engages with responders


Shooter is killed

Access to many offices on the second
floor requires specialized
key cards.


Shooter in lobby


SOURCE: Staff reports. GRAPHIC: The Washington Post.