The report released by the Tarrant County medical examiner's office said Rosa Irene Ayala-Gaona, 52, hit a metal support beam and then fell 75 feet before landing on the metal roof of a tunnel, the Fort Worth Star-Telegram reported Wednesday.
Officials at Six Flags in Arlington have declined to answer any questions about the incident.
A spokesman for Arlington police said the department is "conducting a death investigation" but nothing "points to foul play."
The Texas Giant coaster was originally designed in 1990 as an all wooden roller coaster but it was redesigned with a steel track in April 2011 to mark the theme park's 50th anniversary.
Ayala-Gaona's death prompted officials at Six Flags Fiesta Texas in San Antonio to temporarily close their Iron Rattler roller coaster as a precautionary measure, CNN reported.
U.S. Sen. Edward Markey, D-Mass., Monday called for national safety standards for amusement park rides.