I was driving on the I-10 in Phoenix yesterday, a Saturday afternoon. A City of Phoenix Tahoe started swerving left to right and back again across 6 lanes of traffic with their lights on. Weather was clear, traffic relatively light and no one I saw speeding. This almost caused a multiple car rear end collision as we went from 60 to under 30 relatively quickly. Luckily my exit was in 1/2 a mile after this started (would have exited anyway just to avoid whatever situation this was).