Biological and chemical tests taken at the scene of a Dec. 14 raid at a Niagara Falls residence where 21 police officers and federal agents got sick did not find a cause, authorities said in a joint statement released Thursday morning.
"All collected materials have been tested, both biological and chemical, with negative results," according to the statement from the FBI Buffalo office and Niagara County Sheriff's Office.
Thirty-nine members of local and federal law enforcement conducted a raid at 4 Packard Court. Authorities arrested 28-year-old Jeffrey Richards, after finding cocaine, heroin, marijuana, 10 guns, ammunition and an improvised explosive device, according to authorities.
In the days that followed, 21 people who were at the scene developed a variety of "flu-like" symptoms, officials said. Eighteen others did not get sick.
On Dec. 26, the 914th Air Force Reserve and Niagara County Hazmat went into the residence to take samples for testing.
"Currently, FBI Buffalo and the Niagara County Sheriff's Office are working with the Niagara County Department of Health as it conducts an incident review as to the specific symptoms and illnesses developed after the Dec. 14, 2018, activity at Packard Court," the statement said. "If the incident review results in definitive findings we will release them to the community."
All of the people who got sick have recovered, authorities said.