As horrific images of people running for their lives from bullets flying overhead flooded the media airwaves, there was one question on everyone's lips.
Was the Las Vegas shooting a terror attack?
Las Vegas police have said they do not know the "belief system" of suspected gunman Stephen Paddock, and have not used the label terror to describe it.
When asked whether the massacre described as the "deadliest in US history" amounted to "domestic terrorism", Las Vegas sheriff Joseph Lombardo said "we have to establish what his motivation was first."
US President Donald Trump also did not use the word "terror", describing it as an "act of pure evil" involving the "senseless murder" of Americans.
However some have claimed reluctance to use the term stemmed from the fact the gunman was white, while others asked whether the shooting should be labelled terrorism given the eyewitness video showing people were clearly terrified at the scene.
"Only in America can whiteness prevent the man who conducted the deadliest mass shooting in American history from being called a terrorist," said The Intercept's Shaun King.
Nicole Floyd tweeted "White mass shooters always are mentally ill. Black = gang related. Latino = drug related. Muslim = terrorist"
Others took aim at Trump for being "more enraged by SOB black NFL players kneeling than at act of terrorism by white man Stephen Paddock who killed 50+ in Las Vegas."
Many pointed out that the Nevada State Law describes an "act of terrorism" as one that "involves the use or attempted use of sabotage, coercion or violence which is intended to cause great bodily harm or death to the general population; or Cause substantial destruction, contamination or impairment of: Any building or infrastructure, communications, transportation, utilities or services; or Any natural resource or the environment."
So was it terrorism?
The Collins dictionary defines terrorism as "the use of violence, especially murder and bombing, in order to achieve political aims or to force a government to do something." It's also regarded as the "systematic use of violence and intimidation to achieve some goal."
The Oxford English dictionary describes it as "the unlawful use of violence and intimidation, especially against civilians, in the pursuit of political aims."
Meanwhile Merriam Webster calls it the "systematic use of terror especially as a means of coercion."
Director of International Security Studies at UK think tank RUSI, Raffaello Pantucci, said while it can be a grey area, the main definition of terrorism is when something has a political motivation rather than being based on a personal vendetta or mental health issue.
"That would be the classic response to this question. The difficulty is these days it's very confusing because the nature of what we consider terrorism has changed," he said.
"Whereas it used to be you look for the political motivation and that helped define it, nowadays the act itself has become very difficult [to define.]."
Pantucci said the simple fact of someone being terrified is not enough to label an act terrorism, given that it can happen during natural disasters or wars states wage against one another.
Clearly labelling something in one category or another can also become difficult when acts range from stabbing to running someone over to shooting, based on a combination of mental health issues or personal vendettas overlaid with a political ideology.
"The question becomes are they conducting this act in the purely political way or exercising these other motivations and compounding the political motivation on top?" he said.
"You do have to have some evidence of a political motivation that is more than just an individual lashing out at society."
"[But] the reality is that if you're a person whose lost a loved one, it doesn't matter."