Muslims in cities across the United States walked past heavily armed police officers to attend services Friday, hours after a gunman killed at least 49 people at two mosques in New Zealand. They pored over news reports with a mixture of grief and disgust, feeling familiar fears of being targeted for their religious beliefs.

Throughout a tense day, law enforcement officials and political leaders assured Muslims that they would be protected as they prepared for Friday Prayer, the very thing the victims had been doing when they died.

[Read our live briefing for the latest updates on the attacks.]

The news trickled out overnight in dread-inducing bulletins as the death toll climbed by the hour. The United States is home to about 3.5 million Muslims, or 1 percent of the nation’s population. Some said they had stayed up all night, unable to tear themselves away from the coverage, as difficult as it was to take in.

Nihad Awad, national executive director of the Council on American-Islamic Relations, the country’s largest Muslim civil rights and advocacy organization, said that Muslims around the world were in mourning and that the attacks were part of a rising intolerance in the United States and abroad.