Update: 1:15 p.m., Tuesday

Aaron Alexis, who is now believed to have been the only shooter behind yesterday's Navy Yard mass killing, suffered from serious mental issues, including paranoia and a sleep disorder, and had been hearing voices in his head, according to the Associated Press. 

Alexis also suffered from PTSD, his father told investigators, according to theNew York Times. He had been disturbed by the 9/11 attacks, his father explained; he was an "active participant" in rescue efforts in New York.

Reports coming out of the Navy Yard claim that workers no longer feel safe on the job, knowing that someone like Alexis could be cleared to work at the Navy facility.

Alexis had also sought help from multiple Veterans' Hospitals for psychological issues.

Alexis was in the Navy at one point, but was discharged for misconduct issues in 2011. One of those issues occurred when Alexis allegedly shot a bullet through the ceiling of his apartment.

He was also arrested in Seattle in 2004 for allegedly shooting out the tires of a vehicle in "an anger fueled blackout," according to detectives. 

The Navy has not released what goes into its security checks on outside contractors who work at the Navy Yard or other military facilities.

Update: 4:05 p.m., Monday

Washington, D.C. Police Chief Cathy Lanier is reporting that there are 13 confirmed dead -- including the shooter -- after the shooting at a Navy Yard in Washington, D.C. More than a dozen people are said to be injured.

One suspected shooter has been identified as 34-year-old Aaron Alexis of Fort Worth. He was killed on the scene, but details regarding his death have not been released. Reports say Alexis had recently been hired as a contractor at the Navy Yard.

[ Read more about suspected shooter Aaron Alexis ]

There are conflicting reports on the number of suspects involved with this morning's mass shooting at a Washington, DC Naval facility.

 [ Look at a MAP and TIMELINE of the shooting ]

Lanier said that authorities are still searching for one suspect. Authorities are searching for a black male 40-50 years of age, who was wearing an olive military uniform,  5'10" with graying sideburns.

There is no known motive for the Navy Yard shooting.

Earlier, there were many reports identifying a shooter as Rollie Chance. Those reports have been retracted by NBC and CBS. An employee dropped his name badge and the erroneous reports were based on that.

[ Explore the data on U.S. mass killings since 2006 ]

A mass casualty triage center has been established on the base, which employs more than 3,000 military and civilian personnel.

President Obama's comments on the Navy Yard shootings



- Washington DC Officials: At least 13 dead in Navy Yard shooting

- Flights out of D.C. have resumed following the shooting

- One of the shooters at the Navy Yard has died, officials are still searching for another.

- As a precaution 6 Washington D.C. public schools have been put on lockdown.

- A lockdown at the Senate has been partially lifted following the shooting.

- The Washington Nationals baseball game scheduled for today has been postponed.

- Spokesman confirms one victim was taken to George Washington University Hospital

The White House has issued a statement on the developments:

"The President has been briefed several times about the unfolding situation at the Washington Navy Yard by Assistant to the President for Homeland Security and Counterterrorism Lisa Monaco and Deputy Chief of Staff Alyssa Mastromanaco. The President directed his team to stay in touch with our federal partners, including the Navy and FBI, as well as the local officials.  We urge citizens to listen to the authorities and follow directions from the first responders on site."

The Navy Yard

View Larger Map