U.S. President Barack Obama said Sunday’s mass shooting was an act of terror. It comes as Federal agents say the shooter was “a known quantity” to law enforcement.

CCTV’s Roee Ruttenberg reports.

U.S. federal authorities believe the trigger man in Orlando’s mass shooting on Sunday may have been inspired by ISIL.

This, after a call to 9-1-1 emergency responders, before the shooting spree, in which 29-year old Omar Mateen reportedly pledged his allegiance to the Islamic group.

Speaking after the shooting, U.S. President Barack Obama said he has instructed the F.B.I. to investigate this as an act of terrorism.

“I’ve directed that we must spare no effort to determine what, if any, inspiration or association this killer may have had with terrorist groups,” Obama said.

Authorities had actually interviewed Mateen in previous years, on at least two separate occasions.

In 2014, they said, they were investigating his communications with Moner Abu Salha, a U.S. national who traveled to Syria to train with Al Qaeda’s Al Nusra Front, then returned to the U.S., then went back to Syria, and carried out a suicide bombing, the first American to do so in Syria’s ongoing civil war.

The investigation did not lead authorities to consider Mateen an active threat.

But on Sunday, the ISIL-linked Amaq News Agency released this statement, saying the club attack was carried out by an Islamic State fighter.

It was reminder to many of the December 2015 shooting spree in San Bernardino, California. A husband and wife – believed to be influenced by radical Islam – gunned down 14 people at a holiday work party, before being killed by police.

Prior to Sunday’s attacked, the deadliest recent mass shooting in the U.S. was from 2007. Then, a Korean student killed 32 people on the Virginia Tech campus, before eventually killing himself. There have been others.

Columbine High School, 1999 – two teens killed 12 students and a teacher, before taking their own lives.

In 2012, in Connecticut – 20 children and six adults were killed at Sandy Hook Elementary School.

2015 in South Carolina, a white supremacist shoot and killed 9 people at an African-American church bible study. The list goes on and on.

The classification of Sunday’s shooting as terrorism now allows federal authorities to access specific metadata, and to try to trace down: who the shooter was speaking to, when, what he was reading, and how often. The classification also makes this the deadliest terror attack on U.S. soil since 9/11.

In the past, mass shootings quickly led to a debate about gun laws, which vary from state to state.

In his remarks, President Obama didn’t specifically call for tougher gun policies. But criticize how easy it can be for some to get weapons, and told Americans “we have to decide if that’s the kind of country we want to be.”

Douglas Smith on the next steps into the Pulse mass shooting investigation

Douglas Smith, a former Assistant Secretary at the Department of Homeland Security, gave us some background on how the investigation into the Orlando mass shooting will proceed.