EMBED >More News Videos Investigators said it was too early to tell whether the wreck was caused by a medical emergency or if drugs or alcohol were involved

EMBED >More News Videos Raw video shows the aftermath of a deadly toll booth crash in Houston

HOUSTON (KTRK) -- Disturbing new video shows the moment a speeding truck caused a deadly chain-reaction crash overnight at a Houston toll booth.Investigators now say the driver of a white Dodge Durango that smashed into a Buick at high speed appears to have had a medical issue.The driver of the Buick was killed when the crash sent their vehicle into the back of a pickup truck on the West Sam Houston Tollway.The Buick is nearly indistinguishable after the violent crash left a trail of shattered glass and twisted metal around the toll booth where the three vehicles were stopped overnight.Harris County Precinct 5 Constables said a truck with a small utility trailer was paying a toll when a brown Buick pulled up behind it.While the driver of the Buick was waiting to pay the toll, a white Dodge Durango slammed into the back of it, pushing the vehicle into the back of the pickup truck.The driver of the Durango was transported to the hospital with unknown injuries. Their condition is not known. The pickup truck driver was shaken, but not injured, according to deputy constables.The woman who was working in the toll booth when the accident happened was treated for a minor injury, investigators said.Earlier in the evening, investigators told Eyewitness News the driver of the Durango was moving erratically at a high rate of speed as it approached the Central Plaza in the EZ Tag lane.That is when the Durango crossed over all lanes and hit the back of the Buick sedan.As a result of their investigation, deputies said the driver of the Durango will not be charged.Capt. Terry Thurman said alcohol was found at the scene, but later said the bottle had been sealed.