Flags in the United States will be flown at half-mast until Tuesday in honour of the victims of a mass shooting in a Connecticut primary school.
Twenty school children and six adults were killed when a gunman opened fire at the Newtown Sandy Hook school shortly after 9:30am Friday (local time).
Crowds of grieving residents of the town have held candlelight vigils and attended church services to remember the victims of the one of the worst mass shootings in American history.
Police investigators and medical experts are continuing their investigations and formally identify the victims - most of them aged between five and 10 years old.
Police officials say the 20-year-old suspect Adam Lanza killed his mother at their home before attacking the school, and then killing himself.
Pastor at the St Rose of Lima Roman Catholic Church in Newtown, Monsignor Robert Weiss, says young members of his congregation died in the shooting.
"The reality is settling in that these 20 children are with the Lord now and they've been taken from them too young and too innocent," he said.
"We just told a little boy about his sister now. It's just hard, you know, 'Who am I going to play with?', he said. 'I have nobody to play with now'.
"A lot of these people were from our parish, which makes it pretty heavy for me too. I baptised some of these children."
President Barack Obama urged Americans to join in solidarity as they mourn the victims of a shooting rampage at the school, saying the hearts of parents across the country were "heavy with hurt" for the lives lost.
In his weekly address, Mr Obama said the country needed to set aside politics and "take meaningful action to prevent more tragedies like this".
"As a nation, we have endured far too many of these tragedies in the last few years," he said.
"This weekend, Michelle and I are doing what I know every parent is doing - holding our children as close as we can and reminding them how much we love them.
"There are families in Connecticut who can't do that today. And they need all of us now."
World leaders have expressed shock in the wake of one of the worst school shootings in history.
Prime Minister Julia Gillard said Australia grieves with America at the loss of the school children and teachers.
"Like President Obama and his fellow Americans, our hearts too are broken," she said.
"We share America's shock at this senseless and incomprehensible act of evil."
Recent high profile US shootings:
- Most deadly shooting was Virginia Tech in 2007, where 32 people were killed by a gunman.
- A gunman killed 12 people after he opened fire on an Aurora movie theatre in Colorado in August, 2012.
- Two weeks later a man killed six people at a Sikh temple in Wisconsin.
- Two students shot dead 13 people at the Columbine High School in Littleton, Colorado in 1999.
Follow our live coverage of events as they unfold (all times AEDT):
00:22am: United States police are scheduled to hold a news conference on the mass shooting at the Connecticut school shortly. Watch it live here.
Map: Sandy Hook Elementary School