It was not immediately clear what caused the collision between the Beech 99 and the Cessna 402. An Associated Press article about the accident quoted airport director Barry Bateman who said, "I'm told that one (plane) had just landed and was taxiing into the cargo area. A significant fireball occurred."
Today Airport Business published an update on the accident from the Associated Press. The article says that Freight Runners Express is blaming air traffic control at Milwaukee for the accident.
"Both aircraft were operating in controlled areas under explicit instructions of air traffic control," according to a statement by Freight Runners Express Inc. of Milwaukee.An investigation is underway.