Police sent to Brentwood Stair Road on a report of a minor accident discovered a car in a drainage ditch, police said.
Inside the car, they found a woman dead with an apparent gunshot wound. Next to her in the car was a gun, police said.
Police do not yet know whether the gunshot was self-inflicted or the woman was shot by someone else, spokesman Buddy Calzada said Friday morning.
She will not be identified until the Tarrant County medical examiner has notified her next of kin.
The incident happened just before midnight on Thursday in the 5100 block of Brentwood Stair Road in east Fort Worth, police said.