Details of the shooting in the North Carolina university town of Chapel Hill on Wednesday emerged slowly, with social media users leading the way, ahead of conventional media.
By the time it had garnered national coverage, thousands were posting messages on Twitter with the hashtag #MuslimLivesMatter while dissecting cautious media reporting on the possible motives of the gunman.
Ibrahim Negm, the assistant to Egypt's Grand Mufti, wasted no time in denouncing "the American media's silence on this racist attack", according to a statement from his office.
Ali al-Qaradaghi, the secretary general of the International Union of Muslim Scholars, described the shooter as a "terrorist".
"International media went silent," he wrote on Twitter.
Others underscored what they said was an unusual wariness to ascribe motives to the crime, compared with coverage of militant attacks by Muslims.
Dozens of students staged a demonstration in Gaza yesterday in solidarity with the murder victims.
"We condemn the wilful and unjustified ignorance of the international media in general, and the American media in particular, in the treatment of this case," said protester Said al-Hathom.
The shooter has been identified as Craig Stephen Hicks, 46, who made anti-religious comments on his Facebook page and once uploaded a picture of his revolver.
He describes himself as a "gun toting" atheist.
Neighbours say he always seemed angry and frequently confronted his neighbours, sometimes while wearing a handgun on his hip.
Police are probing whether his apparent hostility for religion factored in his alleged murder of Deah Shaddy Barakat, 23, his wife Yusor Mohammed, 21, and her sister Razan Mohammed Abu Salha, 19. All three victims were shot in the head at close range.
The father of the two slain women says one of his daughters had told him Hicks "hates us for what we are and how we look".
Speaking at a funeral service which attracted 5000 mourners, Dr Mohammad Abu-Salah, a psychiatrist, asked those who had been following the events in Chapel Hill to celebrate the victims' memories.
"Please, think about them," he said. "Celebrate them and believe. This is Islam. It's not what you hear in the media, it's not American Sniper movie. This is Islam. These three angels."
But Chapel Hill police said their investigation thus far pointed to a neighbour dispute over parking.
One news channel interviewed the suspect's wife, who denied the shooting was racially or religiously motivated.
"It's striking that a sort of moderate, cautionary approach is employed when it is a non-Muslim Caucasian killing three young people," said HA Hellyer, a Cairo-based analyst, who works with the Brooking Institute's Project on US Relations with the Islamic World.
"That's the right approach, but it ought to be like that all the time," said Hellyer.