WASHINGTON, DC (RNN) - A gunman who killed 12 people at the Washington Navy Yard before dying in a gun battle with police had a valid pass to access the yard, according to the FBI.
The suspect, 34-year-old Aaron Alexis, is among the 13 who are dead. Born in Queens, NY, he was a military contractor for Hewlett Packard who recently lived in Fort Worth, TX.
CNN reports it may have been his first day on the job, and their sources report that he was armed with an AR-15 semiautomatic rifle, a 9-mm handgun and another rifle. It is believed he used the semiautomatic during most of the attack.
The FBI would not comment on the weapons used. However, they did say he had "legitimate access" to the Navy Yard as a result of his contractor work and that he used a valid pass to gain entry.
Reports circulated throughout the day of a possible second shooter, a possibility Washington, DC Police Chief Cathy Lanier seemingly ruled out late Monday.
"We feel comfortable that we have the single and sole person responsible for the loss of life today," Lanier said.
All the deceased victims were between the ages of 46 and 73 years old. Authorities continued the work of notifying families late Monday.
Although no motive is yet known, details about the suspected gunman's past are slowly coming to light. Alexis was a full-time reservist from 2007 to 2011. He left the Navy on Jan. 31, 2011, as a petty officer third class; he was not discharged but left under a cloud because of a pattern of misconduct.
Law enforcement officials identified Alexis through fingerprints and say he was contractor for the Navy.
Friends in Fort Worth tell CNN Alexis was frustrated about a payment issue from the civilian contracting company, but Michael Ritrovato said he never showed signs of violence.
Shooting began inside the Naval Sea Systems Command Headquarters in Building 197, shortly after 8 a.m. ET Monday. A Metro police officer engaged Alexis, killing the suspect and getting injured in the process.
"We are looking to learn everything we can about his recent movements and associates," said Valerie Parlave, assistant director of the Washington FBI field office.
According to the AP, Alexis was on the fourth-floor atrium shooting into the first-floor cafeteria. He was able to bring three guns into the Navy Yard, according to CNN, one of them being an AR-15.
Lanier said if the suspect hadn't been killed, she believes the death toll would have risen.
"There's no question he would've kept shooting," she said. "I think the actions by the police officers helped reduce those killed. Our hearts go out to the families of the victims."
Multiple agencies are investigating the incident, including the Naval Criminal Investigative Service, DC Metro police and the FBI, which has the lead.
Patricia Ward, a witness who works in Building 197 where the shooting occurred, said that to get on the base, people pass through a metal detector; however, there are no metal detectors to get into the individual buildings. Individual ID badges must be scanned to gain entrance into buildings, like a pass key. Security does not search bags if you have an ID; that is considered clearance for the base.
To get a vehicle on base, a car needs a special window sticker.
Washington, DC, Mayor Vincent Gray said they had no reason to think the shooting was a terrorist attack, but authorities would continue to investigate.
The Navy issued an "Order to Account" for all Navy uniformed personnel, both active duty and selected Reserve assigned to commands in the DC metro area.
A spokesman from George Washington University Hospital said one patient died on the way to the hospital from a single gunshot wound to the head. Also, four or five people were considered in critical condition, with more than 20 noncritical.
Janis Orlowski, chief medical officer of Washington Hospital Center, said they were treating three shooting victims, one of whom was a male Metro police officer who engaged Alexis and received serious injuries to his legs. He is in stable condition. The other two were female civilians.
Orlowski said the wounds appeared consistent with a semi-automatic weapon, but all three are expected to survive. One of the women has a gunshot wound to her shoulder; the other female victim received a wound to her head and her hand.
During the early stages of the incident, emergency responders indicated a "mass casualty" team performed triage at the scene. A U.S. Park police helicopter could be seen removing people from the roof of a building.
Commander Tim Juris told CNN that a maintenance worker tried to warn him about the active shooter situation before he was shot in the head. Juris was helping to evacuate the area.
"[The shooter] was far enough down the hall, and we could see him aim the rifle at us," Terry Durham, a witness, told affiliate WJLA. "He fired at us as we ran down the hall."
Durham added it appeared the shooter was firing over his head. Other witnesses said his weapon looked like a rifle.
The Naval Sea Systems Command's headquarters is the workplace for about 3,000 people, and is comprised of command staff, headquarters directorates, affiliated program executive offices and field activities. It is responsible for engineering, building, buying and maintaining ships, submarines and combat systems for the naval fleet's operational requirements.
The shooting affected the city, already experiencing heightened security after observing the anniversary of the Sept. 11 attacks. A shelter-in-place order was still in effect for surrounding neighborhoods. Eight nearby schools were placed on lockdown, as well as Fort Myer, which is about five miles away in Virginia. The U.S. Senate complex was on lockdown for a couple of hours.
Reagan National Airport put in place a temporary ground stop, and the Washington National's game against the Atlanta Braves was postponed until Tuesday. The stadium is about a mile from the Navy Yard and served as a meeting place for family members.
"I'm deeply shocked and saddened by the shooting this morning at the Navy Yard," said Secretary of the Navy Ray Mabus. "Our thoughts and prayers are with the victims and their families. I have complete confidence in our first responders, and I continue to be completely focused on this very difficult situation."
President Barack Obama spoke about the shooting at a news conference Monday.
"We are confronting yet another mass shooting," Obama said. "It's a shooting that targeted military and civilian personnel. These are men and women who were going to work, to do their job to protect us. They're patriots. We offer our gratitude to the Navy, local law enforcement, federal authorities and the doctors who've responded with skill and bravery."
Obama has directed that flags be lowered to half-staff and remain at half-staff until sunset on Sept. 20.
This is the first mass shooting at a military installation since the Fort Hood incident on Nov. 5, 2009.
Army psychiatrist Nadal Hasan opened fire at the Fort Hood's Soldier Readiness Processing Center in Fort Hood, TX. Thirteen people were killed and 31 were wounded.
In August, a military jury sentenced Hasan to death.
People with information on the shooting can call 1-800-CALL-FBI. Family members looking for information about their loved ones can call 202-433-6151 or 202-433-9713.
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