Four people were killed in an accident, just off southbound Interstate-17 Sunday afternoon. DPS says the accident took place at around 2:18 p.m. and it involved a car and a semi-truck hauling glass. The truck driver told investigators the brakes failed on the truck and he couldn’t stop. The semi exited I-17 at the Sedona/State Route 179 Exit, but failed to stop and collided with the car that was heading north on 179. Both vehicles went off the highway and down an embankment, with the semi-truck coming to rest on top of the car. Both vehicles then caught fire. The truck driver was able to get out of the truck and was not injured. Four people inside the car were killed. DPS says due to the fire intensity, identification of the victims is ongoing. Impairment was not a factor in the accident.