Firefighter-paramedics responded shortly after 11:30 a.m. to the 300 block of East Second Street. They medically assessed several patients who complained of illness "within and outside of an apartment building following their possible exposure to an unspecified substance on a sidewalk," the Los Angeles Fire Department said in a statement. "No escalating or off-site hazard has been identified."
According to LAFD, the substance turned out to be cocaine laced with fentanyl.
Investigators said several police officers were taking part in some kind of police activity when the white powder was spilled on a sidewalk outside an apartment in Little Tokyo.
Two people - both civilians - were taken to the hospital. The patients' conditions were not immediately known.
The LAFD's Hazardous Materials Task Force was summoned in accordance with protocol, the Fire Department said.
A spokesperson for the Alhambra Police Department said officers were serving a search warrant at the scene. No other information about the warrant was available, and it was unclear if the case was connected to the hazmat incident.
The cause of the patients' illness was under investigation.
Second Street was closed between Central Avenue and San Pedro Street. No estimate of when the street would be reopened was given. Drivers were urged to take alternative routes.