(CNN) — A 57-year-old woman was arrested Thursday after an apparent April Fools’ Day joke about a possible active shooter at the manufacturing plant where she works in Springfield, Ohio, the local sheriff’s office.

Pamela Sisco was at the Navistar plant when she texted her sister that a man who had been fired the day before had returned with a gun and they were all hiding in locked offices, Clark County Sheriff’s Office Maj. Christopher D. Clark said in a statement.

Sisco’s sister called authorities at 11:44 a.m. She told the dispatcher she was afraid to text her sister back if they were hiding, CNN affiliiate WHIO reported.

Clark said they scrambled law enforcement to the plant from multiple agencies.

“Every available unit, to include our surrounding villages and townships, responded to the scene and the first Deputy made entry into the facility at 11:46 AM,” Clark said.

Law enforcement units checked the facility and found Sisco, who admitted “she sent the text message to her sister as an ‘April Fool’s Joke,'” Clark said. “No threat of any kind was found to be inside the plant.”

Sisco has been charged with “inducing panic and disrupting public service,” the statement said, but charging documents were not available.

“Ms. Sisco placed a lot of people in harm’s way this morning over a stupid April Fool’s Joke,” Clark said.

It is not clear whether Sisco has retained an attorney at this time.

CNN has reached out to Navistar for comment.

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