Dallas police have opened a criminal investigation into an alleged encounter between civilian spokeswoman Allison Hudson and another driver involving a department-issued vehicle with emergency lights and sirens.

Hudson, the department’s assistant director of media relations and community affairs, is under investigation by its Public Integrity Unit. Police confirmed the inquiry is criminal but did not disclose the specific allegations.

Photographer Avi S. Adelman alleged in a public Facebook post, citing unnamed sources, that Hudson activated the vehicle’s emergency lights, stopped the driver and presented herself as a police officer. The Texas Commission on Law Enforcement said Hudson does not hold a Texas peace officer license. The driver reported the encounter to police; Hudson said the lights had malfunctioned and denied switching them on intentionally, according to accounts citing unnamed sources.

Hudson had not been arrested or charged as of Friday evening, and no determination of wrongdoing had been reported.