President Barack Obama and first lady Michelle Obama attend a memorial for the victims of the Washington Navy Yard shooting. (Photo by Olivier Douliery-Pool/Getty Images)

At a memorial service Sunday to honor the 12 people killed at the Navy Yard this week, President Barack Obama said tragedies like the one that occurred Monday are not inevitable.

“The tragedy and the pain that brings us here today is extraordinary. It is unique. The lives that were taken from us are unique,” the president said to the around 5,000 people gathered at Marine Barracks in Southeast D.C.

“What troubles us so deeply is how this senseless violence that took place in the Navy Yard echoes other recent tragedies,” Obama said, noting the five mass shootings, as well as the everyday shootings, that have taken place during his presidency.

“Once more, we come together to mourn the lives of beauty and to comfort the wonderful families that cherished them,” Obama said. “Once more, we pay tribute to all who rushed toward the danger, risked their lives so others might live.

“Once more, our hearts are broken. Once more, we ask why?”

On Monday, 12 people were killed and eight were wounded when contractor Aaron Alexis opened fire at Naval Sea System Command headquarters at the Navy Yard in Southeast D.C. Alexis was killed by police after they exchanged gunfire, according to authorities. His motive is still unknown.

The president said that the 12 people who died aren’t statistics, sharing personal details about each victim.

“There is nothing routine about this tragedy, there is nothing routine about your loss,” Obama said to the families of the victims.

“It ought to be a shock to all of us,” Obama said of shootings. “It ought to obsess us. It ought to lead to some sort of transformation,” the president continued, noting that other countries like the United Kingdom have taken steps to change laws after tragedies like this.

“Yet here in the United States, after the round-the-clock coverage on cable news, after the heartbreaking interviews with families, after all the speeches and all the punditry and all the commentary, nothing happens,” he said.

“Sometimes I fear there’s a creeping resignation, that these tragedies are just somehow the way it is,” Obama continued. “That this is somehow the new normal.”

“We can’t accept this.”

Obama noted the remarks made by MedStar Washington chief medial officer Dr. Janis Orlowski, who said after the shooting “There’s something evil in our society that we as Americans have to work to try and eradicate.” Orlowski announced she was resigning soon after.

“That’s the wisdom we should be taking away from this tragedy and so many others: not accepting these shootings as inevitable, but asking what can we do to prevent them from happening again and again and again,” Obama said. “I’ve said before, we cannot stop every act of senseless violence. We cannot know every evil that lurks in troubled minds. But if we can prevent even one tragedy like this, save even one life, spare other families what these families are going through, surely we’ve got an obligation to try.”

The president then said “it’s clear we need to do a better job of securing our military facilities and deciding who gets access to them,” and also “do a better job of ensuring that those who need mental health care actually get it, and that in those efforts we don’t stigmatize those who need help.”

But he also said that there’s nothing about Americans that make us inherently more violent. “What’s different in America is it’s easy to get your hands on gun,” he continued.

Obama said he cannot accept that the politics are too “difficult” to make any changes.

“I do not accept that we cannot find a common-sense way to preserve our traditions, including our basic Second Amendment freedoms and the rights of law-abiding gun owners, while at the same time reducing the gun violence that unleashes so much mayhem on a regular basis,” he said. “And it may not happen tomorrow and it may not happen next week, it may not happen next month – but it will happen. Because it’s the change that we need, and it’s a change overwhelmingly supported by the majority of Americans.”

“Our tears are not enough. Our words and prayers are not enough,” Obama continued. “If we really want to honor these 12 men and women, if we really want to be a country where we can go to work, and go to school, and walk our streets free from senseless violence, without so many lives being stolen by a bullet from a gun, then we’re going to have to change. We’re going to have to change.”

Before the president’s remarks, NAVSEA commander Vice Admiral William Hilarides, D.C. Mayor Vincent Gray, chief of naval operations Admiral Jonathan Greenert, Secretary of the Navy Ray Mabus and Secretary of Defense Charles Hagel spoke.

“They loved their country. They loved their Navy. They loved the fleet they helped build and sustain,” Vice Admiral Hilarides said, before saying the news media was wrong to describe the victims as civilians.

“They were killed in the line of duty,” Hilarides said while holding back tears. “For that service, we honor them.”

D.C. Mayor Gray spoke of gun violence: “Our country is drowning in a sea of guns.”

“Senseless gun violence like this is an all too everyday fact-of-life here in the District and in our nation’s our big cities,” Gray said. “It’s a fact of life we must stop accepting.”

Family members of the victims were seated closest to the podium, along with U.S. Attorney General Eric Holder, Del. Eleanor Holmes Norton (D-D.C.), Maryland Gov. Martin O’Malley and representatives and senators from that state.

After religious readings and prayer, including a Hindu reading, the names of the victims were read aloud and marked with the ringing of a bell: 59 year-old Michael Arnold of Lorton, Va.; 53 year-old Sylvia Frasier of Waldorf, Md.; 62 year-old Kathy Gaarde of Woodbridge, Va.; 73 year-old John Roger Johnson of Derwood, Md.; 50 year-old Frank Kohler of Tall Timbers, Md.; 46 year-old Kenneth Bernard Proctor of Waldorf, Md.; 61 year-old Vishnu Shalchendia Pandit of North Potomac, Md.; 51 year-old Arthur Daniels of Southeast, Washington, D.C.; 51 year-old Mary Francis Knight of Reston, Va.; 58 year-old Gerald L. Read of Alexandria, Va.; 54 year-old Martin Bodrog of Annandale, Va.; and 52 year old Richard Michael Ridgell of Westminster, Md.

The service concluded with “Eternal Father, Strong to Save,” better known as the Navy Hymn (“O hear us when we cry to thee/ For those in peril on the sea”) and a playing of “Taps.” The president and First Lady Michelle Obama then hugged the family members of the victims before departing.