Friday marks six years since the Sandy Hook Elementary School shooting in Newtown, and officials across the nation are working to change response methods when it comes to tragedies.

The day has had a lasting impact on American life in so many ways and changed the way law enforcement and everyday citizens approach tragedies.

As a result of Sandy Hook and the epidemic of mass shootings in the U.S., the FBI has partnered with a Texas program known as ALERRT.

According to the program's website, the Advanced Law Enforcement Rapid Response Training was established to help standardize the response to active shooters across federal, state, and local levels.

The Sandy Hook shooting claimed the lives of 20 children and six educators on Dec. 14, 2012. 

Mark Barden lost his son Daniel during the shooting. Barden says he's felt that loss every second of every day since.

But he says this week, his memories of the week leading up to the tragedy have been especially vivid.

In the years since, Barden and other Sandy Hook parents have dedicated themselves to preventing violent tragedies across the country through training and intervention with their group, Sandy Hook Promise.

Barden says it's the best way he can think of to honor the kindness and positivity he saw in his son, right up to their last morning together.

Town offices marked the sixth anniversary with a moment of silence.

According to town officials, all municipal offices, departments, and agencies were closed from 9:30 a.m. until 9:45 a.m. for a moment of silence and reflection in honor and remembrance of the victims of the Sandy Hook shooting.

A memo was posted at town buildings inviting the public to participate in the respite to honor those who were lost.