9900 gauges not functioning correctly

[Redland1]

I was driving last night to an oil well to deliver Frac sand and the traffic light in front of me turned red so I started to downshift.When I came to a stop I saw that the RPm gauge was pegged at 1900 RPM but I could hear that the engine was at idle and also noticed that the coolant temperature was completely at 0 degrees and a low oil pressure light came on.I shut the engine off to reset the gauges and sure enough everything went back to normal.What could have caused this?