HOUSTON, Texas (KTRK) -- A Houston police officer was relieved of duty Tuesday night, charged with driving while intoxicated.Stacey Suro has been with HPD for 24 years. Officers arrested her in the 200 block of Crosstimbers Tuesday around 11 p.m.Eddie Quaid called 911 to report an erratic driver."The person obviously had a medical emergency or was under the influence of drugs or alcohol," Quaid said.He said he saw the car shifting from one lane to the next and running a red light. He added that he continued following the car for about 20 minutes until police arrived."Houston is a very large city. It's a very dangerous city to drive in, and the last thing we need is another drunk driving accident," Quaid said. "I wanted to protect everybody on the road, so I felt like I could do that safely by calling in and continuing to follow the car."According to Eyewitness News sources, Suro failed the field sobriety test and a warrant was issued to have her blood drawn. Responding officers reportedly noticed a strong smell of alcohol coming from her car.Suro allegedly admitted to having three drinks and taking medication for a migraine earlier that evening.Quaid said he did not know the driver he was following was an HPD officer."That's shocking," Quaid said. "It's surprising. But again, anybody that gets behind the wheel under the influence puts other people in danger."Suro was working most recently in HPD's property room as an officer. She was demoted from the rank of sergeant in 2013, disciplined as a result of a misconduct investigation, according to police.An HPD spokesman confirmed Suro was relieved of duty on Tuesday night. An internal affairs investigation will take place.