One teenager died and another was injured when they were thrown from a pickup truck after it collided with an 18-wheeler hauling gravel, police said.

Katy police said the crash happened Tuesday at 4:15 p.m. at the intersection of Katy Mills Boulevard and the Katy Freeway feeder road.  

The passenger of the pickup, Chase Dolan, 18, landed underneath the overturned semi-truck and died at the scene. 

Police said the driver of the pickup truck, Travis Grissom, was also thrown from the vehicle. He was alert after the collision and answered questions, police said.

"One of the vehicles did run a red light. We're trying to determine who," officer Tim Parnell said. "The stories are conflicting.  (Grissom is) saying he had the green light. The 18-wheeler is saying that he had the green light, so the stories are conflicting."

Both are high school students in the Katy Independent School District. Dolan attended Martha Raines High School.

"He never had anything bad to say," friend Collin Goodwin said. "He was the most giving kid ever. It's just horrible what happened to him."

The driver of the semi-truck went to the hospital to be checked out, but police said he did not appear to have any injuries.

Investigators talked to witnesses to try and determine who caused the accident. 

An investigation is under way.