The pickup truck that collided with a tour van near Yellowstone National Park last week is to blame for the crash, which left seven people dead, according to police.Idaho State Police said a Dodge Ram pickup truck crossed the center line on Highway 20 near Henry's Lake State Park and hit the Mercedes tour van, causing both vehicles to burst into flames. It is unclear what caused the truck to leave its lane."Crash reconstruction is ongoing, and ISP troopers are working to determine all contributing factors," state police said on Tuesday.The driver of the truck and six of the 14