Shots were fired Monday inside the U.S. Navy Yard, killing 12 people and the shooter, D.C. Mayor Vincent Gray said.
The incident began about 8:20 a.m. ET when several shots were fired inside the Naval Sea Systems Command headquarters in the southeast portion of the capital.
The injured included a Washington, D.C., police officer who has been hospitalized and another law officer not affiliated with the city force, a police spokesman said.
The dead suspect has been identified as Aaron Alexis, a 34-year-old military contractor from Texas, the FBI said. One other gunman may be on the loose, police said.
10:47 p.m. ET -- Police released the names and ages of seven of the 12 people killed in the shooting. None of the seven was military personnel:
-- Michael Arnold, 59
-- Sylvia Frasier, 53
-- Kathy Gaarde, 62
-- John Roger Johnson, 73
-- Frank Kohler, 50
-- Kenneth Bernard Proctor, 46
-- Vishnu Pandit, 61.
10:40 p.m. ET -- Alexis had access to the Navy Yard because of his contracting work, and he used a valid pass to enter the yard, said Valerie Parlave, assistant director in charge of the Washington FBI field office.
10:39 p.m. ET -- Besides the 13 people who were killed, eight people were injured in Monday morning's shooting, Washington Mayor Vincent Gray told reporters Monday night. Three of those were injured by gunfire, and the others had other types of injuries, such as contusions and chest pain.
Earlier Monday night, Navy Vice Adm. William D. French said 14 people were injured. The 13 dead include suspect Aaron Alexis.
10:38 p.m. ET -- Washington police are confident that only one person was involved in Monday morning's shooting, and they are lifting a shelter-in-place order for residents who live nearby, Police Chief Cathy Lanier said Monday night. Authorities have said suspect Aaron Alexis, 34, was killed after an encounter with security.
10:37 p.m. ET --The ages of those who were killed in Monday morning's shooting at the Washington Navy Yard range from 46 to 73, D.C. Mayor Vincent Gray said. The dead suspect, Aaron Alexis, was 34.
9:37 p.m. ET -- One of the weapons that Alexis is accused of using was purchased recently at a store in northern Virginia, an FBI source with firsthand knowledge of the investigation told CNN's Pamela Brown.
8:43 p.m. ET -- The Washington police officer who had surgery after being shot in his legs is "alert, he's talkative, and he's doing very well," said Janis Orlowski, the chief medical officer at Medstar Washington Hospital Center.
Earlier, CNN's Chris Lawrence reported that doctors will begin to determine on Tuesday whether he will be able to keep the legs.
8:27 p.m. ET -- Besides the 13 people who were killed, 14 people were injured in Monday morning's shooting at the Washington Navy Yard, Navy Vice Adm. William D. French told reporters Monday night. The 13 dead include suspect Aaron Alexis.
8:26 p.m. ET -- About 2,000 people have yet to be released from the Washington Navy Yard after Monday morning's shooting there, though officials hope to let them go in the next three hours, Navy Vice Adm. William D. French told reporters. The military is working with the FBI to process people on the base and release them, and officials are about halfway through the process, French said.
8:05 p.m. ET -- Adding to what we reported earlier about Alexis' movements (see 7:11 p.m. post) - He entered the facility legally with a valid ID card, a federal law enforcement official told CNN's Susan Candiotti.
Alexis used a legally purchased AR-15 shotgun, according to the official.
8:03 p.m. ET -- In Seattle, police say they arrested Alexis in 2004 for shooting out the tires of another man's vehicle in what Alexis later told detectives was an anger-fueled "blackout."
7:53 p.m. ET -- The wounded Washington police officer who was in surgery today at Medstar Washington Hospital Center was shot multiple times in the legs, and doctors will begin to determine on Tuesday whether he will be able to keep the legs, CNN's Chris Lawrence reported.
7:42 p.m. ET -- The names of those killed won't be released until 24 hours after the last relative on the entire list is notified of the deaths, a Pentagon official told CNN's Barbara Starr. This is the same way the Defense Department treats a mass casualty incident in a warzone.
7:11 p.m. ET -- Before the shooting, Alexis drove into the naval yard with his military contractor identification card, a U.S. law enforcement official told CNN's Evan Perez.
Alexis, armed with three guns, walked into Building 197, made his way to an overlook above an atrium, and started shooting, the official said.
6:54 p.m. ET -- Multiple law enforcement sources say that only one weapon was recovered from the scene of the shooting, CNN's Evan Perez and Pamela Brown report. The sources say the weapon was a "long gun."
6:47 p.m. ET -- Michael Ritrovato, a friend and former roommate of Alexis, told CNN that Alexis was frustrated with the company that contracted him to work for the Navy.
Alexis claimed he wasn't paid properly by the company after returning from a months-long assignment to Japan last year, Ritrovato said.
It was unclear whether the dispute was over salary or expenses. Alexis just felt the company owed him money and had not paid him, Ritrovato said.
6:44 p.m. ET -- One of Alexis' friends, Nutpisit Suthamtewakul, told CNN's Ed Lavandera that he had been Alexis' roommate for three years near Fort Worth, Texas, ending a few months ago when Suthamtewakul got married.
Alexis befriended Suthamtewakul four years ago after he emigrated from Thailand, and taught Suthamtewakul about American culture, Suthamtewakul told CNN. Alexis, he said, was fluent in Thai and attended a Buddhist temple.
When Suthamtewakul opened the Happy Bowl Thai Restaurant, Alexis would occasionally help out, waiting tables, he said.
Suthamtewakul reeled at the news that Alexis was believed to be a gunman in the rampage at the Navy Yard.
"I can't believe he did this," he said. "He never showed any sign of violence."
6:20 p.m. ET -- Alexis was discharged from the Navy following a "pattern of misconduct," a U.S. defense official told CNN's Barbara Starr. We previously reported that he left the Navy in January 2011.
6:15 p.m. ET -- Investigators still don't know of a motive in the shooting, D.C. Mayor Vincent Gray said at a news conference moments ago.