On Monday afternoon, as word spread that two bombs had been detonated at the finish line of the Boston Marathon, Imam Ibrahim Rahim found himself alone at Yusuf Mosque on Boston's Chesnut Hill Avenue.
First he offered a prayer for the victims. And then he quietly added: "Dear Lord, God, please whatever this yields, let it not be something that can in anyway be associated with Islam."
In New York, at the same time, Daisy Khan, director of the American Society of Muslim Advancement, had a similar thought, reduced to less than 140 characters: "#ihopeitsnotamuslim."
"My first reaction was I hope it's not a Muslim. I even thought of a Twitter hashtag," said Khan, a leader in the project to build a Muslim community center and mosque near the site of the World Trade Center in lower Manhattan.
The uncertainty around who perpetrated the deadliest terror attack on U.S. soil since 9/11 has left many people anxious. But Muslim Americans await the identity of the perpetrator with particular dread.
"If a Muslim did this it will set the Muslim community back a decade," Khan said. "It will feed into the perception that Muslims are terrorists. Children are more likely to be bullied at school, individuals at work will be treated with suspicion by their coworkers."
Fear of association following a crime is a phenomenon known to nearly every minority in America. But given the scale of 9/11, an attack perpetrated entirely by foreigners, some American Muslims say they are particularly concerned about their faith being associated with the mass killing of innocent people.
It took a number of Muslim American groups days to respond to the Sept. 11 attacks. Within hours of Monday's bombings, however, every major Islamic association in the United States had issued a statement offering condolences, expressing outrage, even directing people on how to donate blood.
In the immediate aftermath of the attack, authorities said they were questioning a Saudi national, who had been injured in the blast. Many Muslims breathed a sigh of relief when investigators said they no longer believed the 20-year-old man was a person of interest, but they still wait with held breath for a suspect to be apprehended.
"Muslims have learned they have to speak out and speak out swiftly," said Khan. "It helps with our perception by other Americans, but it doesn't help keep us from worrying a Muslim is responsible."
Muslims in Boston were invited to participate in today's interfaith service, in which President Obama is speaking, and are planning another event on Friday, the Muslim day of prayer.