ST. LOUIS – Officials say two people are dead after being exposed to a hazardous material in Missouri, MyFOXSTL.com reported.
However, none of the hospitals involved are reporting deaths from the incident.
Authorities were "99 percent" certain the chemical was nitroaniline, a highly toxic material that can cause serious breathing problems and even death.
East St. Louis City Manager Robert Betts confirmed the two deaths, but did not give details, the St. Louis Post-Dispatch reported.
He said the FBI had joined the investigation but that terrorism was not suspected.
Investigators said those hospitalized are employees of the chemical plant Ro-Corp. in East St. Louis.
Chief Jim Silvernail of the Mehlville Fire Protection District said he was told the lid popped off when a drum of the chemical was dropped, raising a cloud of the powder around the workers, the Post-Dispatch reported.
"It's like what would happen if you drop flour — it got all over them," he said.
Eight to ten people exposed to the material were hospitalized around the St. Louis area. At least two people were in very critical condition.
Emergency rooms at two St. Louis-area hospitals were closed Saturday afternoon after several people entered the facilities saying they were exposed to a white powdery substance.
St. Anthony's Medical Center in St. Louis was reopened Saturday night, while DePaul Health Center in Bridgeton was expected to be closed until midnight.
Victims were also transported to Barnes Jewish Hospital, Saint Louis University Hospital and at least one more person was located at Gateway Regional Hospital in Granite City, Illinois.
The workers reportedly showed up at the hospitals with blue skin, prompting the hospital lockdowns, MyFOXSTL.com reported.
Twenty-five people were quarantined inside the ER at St. Anthony's but were allowed to leave by 8:30 p.m.
By Saturday night, the initial victims were being cared for and everyone was released, except for a small group of employees and patients who made contact with the original victims.
The Associated Press contributed to this report.