Deputy exposed to fentanyl via flyer placed on vehicle

Law enforcement in Harris County, Texas, is warning locals to remain alert after flyers placed on deputies' vehicles were found tainted with the drug fentanyl.

The sheriff's office announced Monday that paper flyers, which had been placed on the windshields of roughly 11 to 12 official vehicles parked on the street outside their Houston facility the same day, "have tested positive" for fentanyl.

One sergeant with the force who touched one of the flyers received medical treatment before being released from the hospital, Sheriff Ed Gonzalez told reporters.

The officer "came to her vehicle and found a flyer fixed to the windshield. She picked it up, didn't think nothing of it but as she drove to her destination she began feeling a little bit lightheaded," Gonzalez said, noting she also suffered other symptoms.

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An investigation remains ongoing.

"Fentanyl is an opioid," Gonzalez said. "It's very deadly, it's one of the major concerns in law enforcement these days because of the high number of overdoses that we've seen in other parts of the country."

The sheriff warned nearby residents and locals to be on high alert because officials are not sure if the flyer was intentionally placed on the deputies' cars or if they were "randomly placed here."

Gonzalez said he wants Harris County residents "to be aware of how easily this deadly, toxic opioid could be transferred. It could just be on a simple flyer."

The opioid crisis that has plagued a number of states is killing more than 115 people in the U.S. daily.

The Associated Press contributed to this report.

Nicole Darrah covers breaking and trending news for FoxNews.com. Follow her on Twitter @nicoledarrah or send her an email at nicole.darrah@foxnews.com.