HOUSTON – A Harris County sergeant received treatment Tuesday after touching a flyer laced with fentanyl, according to officials.

Investigators said the flyers were found about 1 p.m. on the windshields of about 12 vehicles parked on the street at the department’s 601 Lockwood Drive facility.

WATCH: Deputy taken to hospital after touching laced flyer

The sergeant removed one of the flyers from her windshield and later began feeling light-headed, according to Harris County Sheriff Ed Gonzalez. She started driving herself to a hospital, but pulled over when she started feeling sick. A lieutenant met her and drove her to the Houston Northwest Medical Center.

It's the first time Gonzalez said he could remember the drug being weaponized.

“I was shocked because this is unprecedented,” said Daryl Shorter, an assistant professor of psychiatry at the Baylor College of Medicine who specializes in addiction. “Fentanyl is a synthetic opioid medication ... used to treat very severe pain, post-operative, post-surgical pain. It’s similar to morphine, but it’s about 50 to 100 times more potent than morphine.”

Images of the flyers included in the tweet showed they contained information about microwave tracking and sonic weapons, with “Attn: FBI, police, firemen” and “Attn: Police & Firemen” written in bold print at the top. They also included the logo of a group called Targeted Justice.

Deputies released these images of flyers that they said were placed on some vehicles at a Harris County Sheriff's Office facility June 26, 2018, in Houston.

“We’re on high alert right now,” Gonzalez said.

Gonzalez said investigators are still trying to determine if deputies were targeted and if there are any more flyers placed elsewhere in the county.

Officials said anyone who finds these flyers should not touch them.

Fentanyl is a powerful painkiller that can be deadly even in small doses.

On the streets, the opioid is usually mixed with heroin or cocaine. Just a few milligrams can cause an overdose. In recent years, first responders around the country have narrowly avoided death after accidental exposure to fentanyl.

“We just wanted to get this information out to the public because we don’t know if it’s an isolated incident,” Gonzalez said.

The Harris County Sheriff’s Office put out a statewide alert, warning law enforcement to watch out for the potential threat.

The group Social Justice released the following statement Wednesday:

"Targeted Justice is a human rights organization.

We stand for the US Constitution and the American values of life, liberty, and the pursuit of happiness and the importance of the inalienable rights of the individual. We stand against cruelty, violence and injustice wherever it comes from, even from a perversion of authority. We thus far have a membership of over 500 and are growing. All are victims of a staggering range of human rights violations, and as such, we do not endorse any activity that could endanger or harm another human. We were quite relieved to hear that the officer who allegedly came into contact with a tainted flyer bearing our information, is perfectly fine.

We are awaiting more information as to who may have printed off the flyer in question from our website, where it is readily available to anyone. And who, if anyone may have somehow put a noxious substance on it for unknown purposes, which we have been informed is a common street drug, common in any police or sheriff's department evidence storage. When an organization puts together an informative flyer it is not logical to scare people away from reading it. We can only assume, this was a desperate move done to censor information the public needs to know for its own safety. In regard to our group being reported as antigovernment, it is truly alarming to see people in the press jump to illogical conclusions without consulting anyone in our organization.

Our core, founding members are spread all over the country and are a combination of entrepreneurs, two Federal workers, one retired, an older legal student on his second career, and other highly educated professionals. I personally spent my career as an intelligence analyst with the National Security Agency, so dedicating one's life to the protection of one's country can hardly, logically or correctly be called anti-government.

We await a full and complete investigation of this incident and support the prosecution of anyone who would harm an innocent person. At this point in time, members Ella Free and Karen Stewart are the only members authorized to speak for Targeted Justice."