The 27-year-old woman said she was driving when a man wearing a dark blue uniform stopped her for a traffic violation around 3 a.m.
She said the man handcuffed her and put her in the back of his black Ford Crown Victoria that had emergency equipment and white lettering.
The man then drove the victim to an unknown location and sexually assaulted her, according to investigators.
The suspect is described as a light-skinned black male in his late 20s to early 40s. He is more than 6 feet tall and weighs about 240 pounds with a muscular build.
Police urges anyone with any information to contact HPD Special Victims Division at 713-308-1140 or Crime Stoppers at 713-222-TIPS.