Police say an off-duty officer who caused a chain-reaction wreck that killed a Kansas teen was driving a department van too quickly when he slammed into the teen's car as traffic slowed to turn into Arrowhead Stadium for a Kansas City Chiefs game.

The Kansas City Star reports that the police report was issued Wednesday for the Oct. 21 crash that killed 17-year-old Chandan Rajanna, of Overland Park, Kansas, and seriously hurt his father and older sister.

The document says witnesses reported that the van was going as fast as 70 mph when it started braking about 30 feet from the stopped traffic. It says the driver was "unable to stop, or avoid the vehicles in front of him."

Besides the van and car, two other vehicles also were struck.