President Obama spoke to a capacity crowd at Newtown High School's auditorium during Sunday's vigil for Sandy Hook Elementary School shooting victims. (Neon Tommy archived screenshot)

Obama visited with parents of students killed in Friday's shooting at Sandy Hook Elementary School. He also met with emergency crews who responded to the shooting conducted by a 20-year-old gunman who killed his mother and 26 victims at the school before committing suicide.

The president spoke to a capacity crowd of 900 people, who packed the Newtown High School auditorium to attend the service.

“I am very mindful that words cannot match the depths of your sorrow,” the president said. “But whatever measure of comfort we can provide, we will provide. … Newtown you are not alone.”

More from NBC News:

Obama asked whether America was doing enough and bluntly concluded: "No. And this must change."

"We can't tolerate this any longer," he declared. "These tragedies must end."

The president challenged the audience asking: "Are we prepared to say that we're powerless in the face of such carnage? That the politics are too hard? Are we prepared to say that such violence visited on our children year after year after year is the price of our freedom?"

He vowed to "use whatever power this office holds to engage our citizens ... to save another child or another parent or another town" the anguish of Newtown.

Obama spoke at a podium, in front of which stood a table with 26 white candles representing the victims of the massacre. This was the fourth trip of his presidency to a city recovering from a mass shooting.

Toward the end of the speech, Obama read the names of the victims. Twenty of the dead were between the ages of 6 and 7 years old.

"God has called them all home," the president said.

Find more Neon Tommy coverage on the Connecticut shootings here.

Reach Executive Producer Danny Lee here; follow him here.