Nineteen children and two teachers were killed on Tuesday, when an 18-year-old gunman stormed into Robb Elementary School in Uvalde, Texas and locked himself in a fourth grade classroom.
Salvador Ramos, 18, had an AR style assault rifle on him and had recently legally purchased two weapons and more than 1,600 rounds of ammunition.
Authorities said they found more than 300 rounds inside the school including 142 bullets that had been fired.
The president and his wife lay a bouquet of flowers at a memorial site to the victims that has sprung up outside of Robb Elementary in the days since the attack. They then solemnly inspected portraits of the victims that have been left at the site. The first lady and president could be seen on video touching some of the photos. The two then attended mass at Sacred Heart Catholic Church just a kilometre from the school.
The attack in Uvalde is the deadliest school shooting in the US since 2012, when 26 people, including 20 children, were killed at Sandyhook Elementary School in Newtown, Connecticut.
It has shaken the community of 15,000 to its core and once again ignited a furious and often repeated debate on gun control in the US.
Thousands gathered outside the National Rifle Association’s annual convention held in Houston, Texas, just a four drive from Uvalde, to protest against America’s biggest gun lobby.
Former President Donald Trump, who headlined the event, denounced calls for gun regulations and said now was a time to “unite”.
Police have been heavily criticised for failing to intervene in the attack earlier. On Friday, it was revealed that 19 police officers were in the hallway waiting to breach the classroom door for 45 minutes.
“Of course it was not the right decision. It was the wrong decision,” said Steven McCraw, Texas Department of Public Safety Director.
"From what we know, we believe there should have been an entry as soon as you can," he added.
Texas Governor, Greg Abbott, who initially praised law enforcement's response has had to walk back his previous comments.
"I was misled," he said at a news conferencing on Friday. "I am livid about what happened."
"Those are families whose lives have been destroyed. They need answers that are accurate and it is inexcusable that they may have suffered from any inaccurate information whatsoever," he added
President Biden was expected to meet with families of those killed in Tuesday’s shooting as well as survivors later on Sunday.
The president was also expected to meet with first responders.
Mr Biden’s trip to Uvalde was the second time in two weeks he had travelled to comfort an ailing community.
Earlier this month, he visited Buffalo, New York after a gunman opened fire at a shopping centre, killing 10 people, in what authorities have said was a racially motivated attack.
Agencies contributed to this report