The letters arrived in March. Sent anonymously to multiple communities, they declared that Tuesday, April 3, would become ‘‘Punish a Muslim day’’ in the United Kingdom.

Sent to homes, lawmakers, and at least one business, the documents detailed a disturbing point-based system that would award attackers for acts of hatred and violence: 10 points for verbally abusing a Muslim; 500 points for ‘‘butchering a Muslim using a gun, knife, vehicle, or otherwise.’’

Police launched an investigation, urging communities to stand together.

A spokesman for the Metropolitan Police service told London’s Evening Standard that there was no credible information that any hate crimes would happen. By Tuesday night, there were no news reports of hate crime incidents.

At a time when hate crimes are on the rise, the letters caused distress, not just to those receiving them but also in the broader Muslim community. As April 3 approached, many took to social media to share their thoughts on the hate campaign.

On Tuesday, many Brits returned to work after the four-day-long Easter break. For Muslims, the day was filled with a heightened sense of anxiety. By lunchtime, #PunishAMuslimDay had been used over 26,000 times and was one of the top Twitter trends in the United Kingdom.

Angry at the lack of reassurance or response from the government, many demanded answers.

‘‘This government condemns any attempt to sow hatred- persecution of anyone based on their race or religion has no place in our society,’’ Susan Williams, a Home Office minister in the House of Lords, tweeted Tuesday using the hashtag #WeStandTogether.