Nearly two dozen people were evacuated from a Washington state courtroom Thursday after a piece of drug evidence containing fentanyl residue was opened during trial proceedings, triggering a hazmat response.

The incident unfolded around 11:55 a.m. inside a second-floor courtroom at the Snohomish County Courthouse in Everett, according to the Everett Fire Department.

An evidence envelope, initially reported as a bag containing a scale, was handled and opened in court. The scale later tested positive for fentanyl residue. It remains unclear why the envelope was opened during the proceedings.

“One person thought that they saw a small powder that kind of came off the scale,” Rachael Doniger of Everett Fire told KOMO.

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Out of an abundance of caution, everyone in the courtroom was relocated to the courthouse’s fourth floor for medical evaluation. Crews checked vitals and blood pressure and monitored for potential overdose symptoms, including unconsciousness or difficulty breathing, officials said.

“No one showed any symptoms or was taken to the hospital,” Doniger said, adding that all individuals were released to go home.

The second-floor courtroom was shut down by the Snohomish County Sheriff’s Office while a specialized hazmat team cleaned and secured the area.

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The unusual incident raised questions about how drug evidence is handled inside courtrooms.

Mark Lindquist, the former district attorney for Pierce County and a former trial chief of the Pierce County Drug Unit, told KOMO he had never heard of a courtroom being cleared over potential drug exposure.

“Either somebody dropped the ball here or a rule needs to be changed,” Lindquist said.

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He added that drug paraphernalia should be securely stored in an evidence room and questioned why photographs were not used during the Snohomish County trial instead of the physical scale.

“This is the first time I’ve ever heard of a courtroom being cleared because of potential exposure to drugs,” Lindquist said. “And it highlights why prosecutors use pictures rather than the actual drug.”

When asked whether an investigation was underway, the Superior Court told KOMO it is looking into all the circumstances and reviewing policies and procedures to prevent something similar from happening again.

“We take all matters impacting staff and court users very seriously, especially with regard to the spaces in which the public frequently occupies,” a statement from the court said. “We are committed to taking all steps necessary to make sure events like this don’t happen again, including examining policies and procedures and working collaboratively with stakeholders.”

Officials said the exact quantity of fentanyl residue involved remains unknown. There was no visible plume or indication of a significant airborne release.

​Nearly two dozen people evacuated a Washington courtroom after fentanyl residue was found on a drug evidence scale, triggering an emergency hazmat response and safety concerns.