According to the Washington State Department of Transportation (WSDOT), they are still trying to determine what prompted the woman to take the truck, which was one similar to the one pictured in our story.

Early morning robbery ends in 20-minute chase

Around 4 a.m. Wednesday morning, WSDOT crews were conducting road work on I-405 when one of their traffic control vehicles suddenly drove off.

Emergency crews were working near the intersection of I-405 and I-90 when the large truck, loaded with traffic cones, lights and movable safety barriers, slowly rolled away. These trucks are not designed for high speeds, so it just kept rumbling down the highway, and the Washington State Patrol, as well as Bellevue and Kirkland police, quickly joined the pursuit.

Because of the slow speed, authorities were able to plan well in advance, and after the truck stopped and started driving again, they were able to set up spike barriers. WSDOT officials say this apparently frightened the woman driving, who stopped and surrendered.

No results have been released on whether toxicology tests were conducted, but WSDOT says officials are trying to determine if drugs or alcohol were involved. Officials are focusing on how she was able to gain access to the vehicle and how to prevent similar incidents in the future.