More than a hundred Pelican Bay State Prison employees were quarantined after a suspicious substance was found in a letter. The employees were reportedly released the following morning.A statement from the California Department of Corrections and Rehabilitation (CDCR) said a letter that claimed to contain a suspicious substance was received Tuesday, July 23, in the administration building at the prison. Investigators sealed the letter in a bag to contain the threat of exposure and the building was evacuated.No injuries were reported and an investigation is ongoing. Prison officials from the state are working with local, state and federal law enforcement agencies to identify the substance contained in the letter. CDRC said local law enforcement was considering potential secondary exposures and taking necessary steps to mitigate safety concerns.A Humboldt County-based hazardous material team was called to the prison the day the letter was received. Preliminary testing was done and the FBI is conducting follow-up testing of the substance inside the envelope.#placement_573654_0_i{width:100%;max-width:550px;margin:0 auto;}var rnd = window.rnd || Math.floor(Math.random()*10e6);var pid573654 = window.pid573654 || rnd;var plc573654 = window.plc573654 || 0;var abkw = window.abkw || '';var absrc = 'https://ads.empowerlocal.co/adserve/;ID=181918;size=0x0;setID=573654;type=js;sw='+screen.width+';sh='+screen.height+';spr='+window.devicePixelRatio+';kw='+abkw+';pid='+pid573654+';place='+(plc573654++)+';rnd='+rnd+';click=CLICK_MACRO_PLACEHOLDER';var _absrc = absrc.split("type=js"); absrc = _absrc[0] + 'type=js;referrer=' + encodeURIComponent(document.location.href) + _absrc[1];document.write('');CDCR assistant secretary Jeffrey Callison said results of the FBI analysis have not yet been received. He confirmed that the prison’s administration building remained closed as of press time.Terry Thornton, CDRC deputy press secretary, gave a statement to news station KRCR in which he said 116 employees who work in the administration building, mailroom and warehouse were put on a precautionary quarantine because of the suspicious letter. He said the employees were released Wednesday morning with no signs of illness or injury.Operations at Pelican Bay State Prison are otherwise normal and the inmate population is unaffected, according to Thornton. Centinela State Prison reportedly received a similar letter and evacuated staff from its mailroom. There were no injuries reported in that incident either. googletag.cmd.push(function() { googletag.display('ad-1515727'); });