The West Des Moines Police Department issued new details Monday about a fatal collision between a vehicle and fire truck.
The collision that happened last month killed 16-year-old Erika Schwager.
The Urbandale Police Department and the West Des Moines Police Department investigated the crash.
The information was given to the Polk County Attorney's Office.
Investigators found that Schwager was driving westbound on Westown Parkway at about 30 to 35 mph and the West Des Moines fire truck was headed northbound on Valley West Drive at no more than 35 mph, a news release said.
The fire truck's lights and sirens were activated and all vehicles nearby had stopped or slowed down, except Schwager's, the release said.
The investigation showed that Schwager had a green light and failed to yield to the fire truck even though the emergency vehicle had a red light.
"Erika did not yield to the emergency vehicle. The fire truck had its red lights and sirens activated," said Lt. Jeff Miller of the West Des Moines Police Department.
The fire truck also had a red light. A safety measure inside that fire truck called a pre-emptive device was supposed to change it to green, but it didn't, NewsChannel 8 reported.
"The fire truck had activated their pre-emptive device prior to the accident at 35th and Westown Parkway ... It had pre-empted some other lights leading up to it and for reasons unknown it didn't pre-empt that particular light," Miller said.
"Your pre-emptive button is right here we leave it on all the time and then it goes off automatically when you put it into park," said Brian O'Keefe of the Des Moines Fire Department. "So anytime you turn the emergency lights on the pre-empt device transmits a signal."
That signal is sent to a box on top of the truck, to another on a utility post and then the traffic light changes to green before the fire truck enters the intersection.
"So it just helps move the vehicles out of the way in an orderly fashion so we can proceed through the intersection and we're not obstructed or slowed down by vehicles," O'Keefe said.
Miller said the city plans to look into the pre-emptive device and the collision.
"The Schwager family wishes once again to express our appreciation for the support and encouragement we have received from so many people during this difficult time. The findings of the report does nothing to change our desire to pray for the well-being of all involved and to move on with our grieving process," the Schwager family said in a statement.
The Polk County attorney now has the police report, but no charges are expected to be filed.