U.S. authorities have yet to say what might have been the motive of a 20-year-old gunman in a mass shooting that killed 20 young children and six adults at an elementary school in the town of Newton, Connecticut.

Hundreds of mourners descended on a church in Newtown Friday night to grieve the deaths, as the community and the nation sought to absorb the scope of the tragedy. Governor Dannel Malloy told the mourners “evil visited this community today.”

On Saturday, U.S. President Barack Obama said in his weekly address every parent in America has “a heart heavy with hurt.” He called for “meaningful action” to prevent more tragedies.

His remarks were similar to comments he delivered Friday, just hours after horror and mayhem struck at the school in the small community 130 kilometers northeast of New York. In Washington, the tearful president said “our hearts are broken” by the deaths.

Witnesses say the gunman dressed in black military fatigues entered the school at mid-morning Friday, opening fire on children and their teachers in two rooms. The principal of the school was among those killed.

Officials say the shooter, identified as Adam Lanza, died at the scene of a self-inflicted gunshot. Two semi-automatic handguns were found nearby. A military assault rifle was later found in the gunman's car.

Authorities say the shooter killed his mother at her home where he also lived, then drove her car to the school where witnesses say he opened fire without saying a word.

The gunman's brother was taken by police for questioning late Friday in New Jersey. Police say he is cooperating in the probe.

Video from the crime scene showed children being rushed from the school single file, people hugging, and frantic parents either waiting for word on their children or hugging them once found. It took several hours before the full scope of the tragedy became public.

The usual Republican Party address Saturday was not delivered. Republican leaders said this was a time for the president to speak for the nation.