OVERNIGHT DEFENSE: 13 dead in mass shooting at Washington Navy Headquarters

“We don’t know what the motive is at this stage,” Washington Mayor Vincent Gray said. “We don’t have any reason at this stage to suspect terrorism but certainly it has not been ruled out.”

Read more about Monday's shooting here, including reactions from witnesses inside the building where the shooting occurred.

Lawmakers lash out on 'cowardly' act of violence: Congressional lawmakers were shocked and saddened by the "cowardly" actions of a former Navy sailor who went on a shooting rampage at the service's Washington D.C. headquarters Monday. 

"There is nothing more cowardly than targeting innocents, and we have full faith in military and law enforcement officials to bring the perpetrators to justice," House Armed Services Committee chief Rep. Buck McKeon (R-Calif.) and ranking member Rep. Adam SmithAdam SmithCongress, authorize fresh base closures to strengthen our military GOP lawmaker drops effort to force vote to extend DACA protections Trump officials brief lawmakers on North Korea MORE (D-Wash.) said in a statement. 

On Monday, 13 people were killed and several more wounded when a gunman opened fire at the Navy's headquarters in Washington. The alleged shooter, Aaron Alexis, 34, of Fort Worth, Texas, was among those killed, according to D.C. police. 

"Today’s horrendous act [was] made all the more terrible because it happened in a place and to people who serve our nation and work to protect us," Sen. Jay RockefellerJay RockefellerOvernight Tech: Trump nominates Dem to FCC | Facebook pulls suspected baseball gunman's pages | Uber board member resigns after sexist comment Trump nominates former FCC Dem for another term Obama to preserve torture report in presidential papers MORE (D-W.Va.) said in a statement. 

“This is one more event to add to the litany of massacres that occur when a deranged person or grievance killer is able to obtain multiple weapons ... and kill many people in a short amount of time," Senate Intelligence panel Chairwoman Dianne FeinsteinDianne Emiel FeinsteinDems call for action against Cassidy-Graham ObamaCare repeal Feinstein pushes back on Trump’s N. Korea policy Feinstein on reelection bid: ‘We will see’ MORE (D-Calif.) said in a separate statement. 

Feinstein spearheaded a failed effort to enact tougher gun control regulations in the wake of the mass shootings at Sandy Hook elementary school in Connecticut last year. 

Navy reviews security measures: Navy leaders are taking a hard look at security measures at their bases and installations in the wake of Monday's shootings at the Navy's headquarters in Washington, D.C. 

Security measures in place at the Navy Yard in Southeast Washington, D.C., are comparable to measures in place at several of the service's major installations in Virginia and California. 

All military members and civilians at the Navy Yard and elsewhere are subjected to "100 percent" identification checks and are required to pass through multiple checkpoints before coming on base property, according to a Navy official.

Aside from identification checks, military personnel are also required to show their Common Access Card, or CAC card, before going on base.

A CAC card is assigned to all service members, allowing them access to military-only facilities, the official added.

While an individual's identification is always checked visually, those cards or other ID cards are only occasionally scanned via computer to verify their validity.

Forged military or civilian IDs are "always a concern," according to the service official. But the official noted that members of the service's base security force are trained to spot falsified or doctored identification or CAC cards.

Obama waives arms regs for Syrian rebels: President Obama has waved federal regulations on U.S. arms sales to begin supplying anti-chemical-weapons equipment to rebel forces in Syria. 

"This action will allow the U.S. Government to provide ... where appropriate, certain non-lethal assistance inside or related to Syria" related to equipment needed to survive a chemical weapons attack, according to National Security Council spokeswoman Caitlin Hayden. 

The United States is prevented from shipping gas masks and other "non-lethal" protective equipment related to chemical weapons use under mandates in the Arms Export Control Act. 

Obama's announcement effectively eliminates those rules for "international organizations ... [and] select vetted members of the Syrian opposition, including the Supreme Military Council," Hayden said in a statement Monday. 

"This action is part of longstanding and ongoing efforts to provide life-saving chemical weapons-related assistance to people in need in Syria," Hayden added. 

The order comes as U.S. and Russian officials are working a disarmament deal to force Syrian President Bashar Assad to give up his chemical weapons stockpiles. 

Secretary of State John KerryJohn Forbes KerryBringing the American election experience to Democratic Republic of the Congo Some Dems sizzle, others see their stock fall on road to 2020 The Hill's 12:30 Report MORE and Russian Foreign Minister Sergey Lavrov agreed to the deal, which would have Assad hand control of those stockpiles to the United Nations.  But serious questions remain on how international regulators will be able to track and contain those weapons stockpiles. 

Army Lt. Gen. Michael Flynn, head of DOD intelligence, said Thursday it could take as long as seven years to fully account for Syria's stockpile if a deal is reached.

"I do not have a [high] level of confidence to get through this first iteration" of getting the weapons accounted for, he said.

"I'm hopeful that there's clear, cool-headed ... very long-view thinking and decision-making done," on how to secure the Syrian weapon sites, Flynn said. 

In Case You Missed It: 

— Report: Turkish jets shoot down Syrian aircraft 

— Gates to pen Washington tell-all book

— Navy Yard eyewitness: 'Pop, pop, pop' 

— Navy eyes base security measures

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