Kacey Musgraves' Tour Bus Helps Driver After Rollover Crash

Kacey Musgraves' tour bus came to the rescue after a man's pickup truck rolled over on an Arizona highway ... TMZ has learned.

The Arizona Department of Public Safety tells TMZ ... troopers responded to a Toyota Tundra rollover on Southbound U.S. 93 just outside Kingman around 12:15 PM Friday ... and eyewitnesses say the pickup veered off the road and flipped.

We're told one of Kacey's tour bus drivers stopped to help the man and stayed with him until paramedics arrived. Kacey has a show in Phoenix on Saturday, and it sounds like her tour buses were in the right place at the right time.

According to officials the bus driver was a former firefighter and actually helped extricate the driver.

Folks who were there say the driver's wife was following behind in another vehicle with their dog ... and the pup is safe.

Officials tell TMZ ... the driver was alert and responsive after the crash and was transported to a local hospital with minor injuries.

Sources close to Kacey tell TMZ ... the singer was NOT on the tour bus when it pulled over, and the tour will continue as scheduled.