Phoenix – A bus carrying Dallas Cowboys staffers, but no players, and a van collided on an Arizona highway on Sunday, killing four people in the van, authorities said.The bus occupants emerged uninjured from the crash, Arizona Department of Public Safety (DPS) spokesperson Quentin Mehr said.The scene of a bus crash on a highway in northwestern Arizona after a Dallas Cowboys bus collided with another vehicle. (Cody Davis/Kingman Daily Miner via AP) "All on the bus came through OK with some bumps and bruises," Cowboys spokesperson Rich Dalrymple said in an email. Dalrymple said the bus was only carrying members of the franchise's staff but would not say how many. There were no players on board.Mickey Spagnola, a columnist for the team's website, has been writing for the past week about travelling on a Cowboys bus with a driver, the team mascot and videographer. On his Twitter page, Spagnola tweeted before 14:00 that the bus was 128km outside of Vegas.Road Trippin' 2016 about 80 miles outside Vegas, our next stop, 3 pm GameWorks pic.twitter.com/4Xav0wBoTR— Mickey Spagnola (@Spags52) July 24, 2016The two vehicles collided in the afternoon on US 93, about 48km north of the city of Kingman or 288km northeast of Phoenix, according to DPS. The crash shut down at least one lane of the highway that serves as the main route between Las Vegas and Phoenix.The bus was on its way to a Dallas Cowboys fan event in Las Vegas. Charles Cooper, manager of GameWorks entertainment centre in Vegas, said the session with 50 to 75 fans was scheduled for 15:00 (PDT).People were already waiting when the president of a Las Vegas Cowboys fan club called to relay news of the accident. The event was subsequently cancelled. Cooper says the team mascot was supposed to appear.After the Las Vegas stop, the bus was scheduled to go on to Oxnard, California for the team's training camp. Members of the organisation typically take a bus two weeks before the camp starts and make stops along the way.