Four gay men have been stabbed in New York City's Prospect Park since June, putting both police and park visitors on alert, The New York Times and New York Post report.
All four attacks have taken place within half a mile of each other, three of them at night and the most recent during the day.
The city has offered a $12,000 reward for information leading to an arrest. The attacker has been described as a Black man in his 40s, 6' 1", 185 pounds. The Post dubbed him the "Ninja" slasher for his tendency to wear black and to adopt Ninja movements.
The New York State Black Gay Network has urged police to practice care.
"It must be made very clear," wrote Nguru Karugu, the network's coordinator, that "while the suspect of these acts is described as a Black male, this does not automatically mean that all Black men going through Prospect Park should be harassed or mistreated by the police."
The New York City Gay and Lesbian Anti-Violence Project and People of Color in Crisis, an alliance of Black gay men, announced that they would distribute whistles to people in the park and post fliers to warn visitors about the attacks.