By the time you read this, the story of the Boston Marathon terror attack may be quite different from the one told by the media on the day. Last December's Sandy Hook massacre, after all, demonstrated the rule of thumb for media coverage of mass killings in America: "facts" reported in the first hours after the event often turn out to be untrue.
In the case of the Connecticut school shooting, the media initially got the shooter's name wrong, wrongly claimed that his mother had worked at the target school, that he'd been buzzed in as a familiar face, and that his mother was part of a right-wing survivalist cult.
Indeed, unverified "facts" whizzing around in the media hours after a double bombing at the Boston Marathon are already defining, in some minds, the most significant terror attack on US soil since September 11, 2011. This attack has already killed three people and wounded more than 140. And although the scale of the casualties may not remotely resemble that of 9/11, this was nonetheless the first successful multiple-casualty bombing on American soil since the attacks that defined US national security posture for a decade.
Until now, the domestic terror threat in the United States had been confined to amateurish plots infiltrated and disrupted by law enforcement agencies, and one or two bombs that failed to detonate. This time, two ball-bearing-packed explosive devices (described by FBI sources to the Los Angeles Times as "amateurish") detonated within seconds of one another, leaving Boston's streets bloodied and Americans in shock at this brutal reminder of their continued vulnerability to politically-motivated violence.
And in the resultant climate of fear, despite the impeccable reporting of many media outlets, some more unfortunate familiar patterns also began to assert themselves.
As of late Monday night, the website of the tabloid New York Post was carrying a story claiming that an unnamed 20-year-old Saudi man was a "suspect" in the terror attack, and was being kept under guard at an undisclosed hospital where he was allegedly being treated for burns. The story was attributed to "law enforcement sources". The same story claimed that 12 people had been killed in the twin bomb blasts, and 50 injured.
This was hours after the Boston Police Department's spokesman had denied that any suspect was being held, and the police commissioner had insisted that none of those with whom the police were talking in hospital had been named as a "suspect". It was also long after the official death toll stood at three, with more than 100 people wounded.
But the Post's "Saudi suspect" story was snowballing. Right-wing web sites were using it to link the bombing to the 9/11 attacks in which most of the hijackers were Saudi nationals, and even mainstream outlets such as NBC were embellishing the story, reporting that , "According to the New York Post, authorities have arrested a Saudi Arabian national in connection to the explosions." Actually, the Post had never reported that an arrest had been made. But the tabloid was quite happy to play the echo chamber game itself, reporting later on Monday night that "CBS reported that an individual is in custody. He is reportedly cooperative and denies involvement in the attack."
Later the same night, The New York Times weighed in with this explanation: "Although investigators confirmed that they were speaking to a Saudi citizen, several law enforcement officials took pains to note that no one was being held in custody. While the authorities have not arrested the Saudi man, he has remained at a hospital under close supervision by law enforcement authorities, according to a senior law enforcement official."
Perhaps. But unless the police have evidence that the Saudi committed a crime, journalism-school sophomores know it's irresponsible to recklessly label him a "suspect". And who knows what turns the story will take in the coming hours.
The tale of the "Saudi suspect" notwithstanding, of course, most mainstream US media outlets remained relatively sober, largely avoiding speculation over authorship - and devoting a considerable portion of such speculation as they allowed to exploring the possibility that white right-wing, domestic extremists may have been responsible. Some, though not all, heeded President Barack Obama's urging that "people shouldn't jump to conclusions before we have all the facts".
Critics elsewhere complained about the extent of attention on the Boston bombing by global media - after all, they said, 55 people were killed in attacks in Iraq the same day, and dozens more in recent days in Afghanistan, Somalia and elsewhere, while Syria's grotesque bloodletting continues unabated.
But here's the brutal logic of news editors: the Boston attack is unique precisely because - unlike the carnage in Iraq, Somalia, Afghanistan and Syria - it's anything but an everyday event.
There's a second reason why editors the world over are paying obsessive attention to the events in Boston: they remember all too well how the last terrorist attack on US soil was used to goad Americans into two disastrous wars of occupation.
And yet the chastening effect of those wars on the American body politic make further military misadventures unlikely, even if - and that's a big if - the perpetrators of Monday's attack prove to be motivated by the cause of global jihad.
"We have to get back to the place where terrorists are not the focus of our lives, but they're a nuisance," one senior US politician told Americans in 2004, comparing terrorism to organised crime. "It isn't threatening people's lives every day, and fundamentally, it's something that you continue to fight, but it's not threatening the fabric of your life.''
The response to Boston could measure how far America has travelled down that path away from the hysteria that followed 9/11. It's reassuring, of course, that the politician who sketched this sober-minded response to terrorism, Senator John Kerry, today serves as secretary of state.
Tony Karon is an analyst based in New York
On Twitter: @TonyKaron