In the late morning of June 20, 2003, a string of 31 freight cars that had been part of a Union Pacific Railroad (UP) freight train were cut from their locomotives at a UP siding in Montclair, California. After crewmembers released the cars’ air brakes in preparation for switching the cars in Montclair yard, the cars began rolling. The runaway cars rolled downgrade for about 28 miles and reached a calculated maximum speed of 95 mph before derailing in City of Commerce, California, at 11:58 a.m. Some of the derailed cars struck nearby residences. Three residences were destroyed, and five others were damaged. Thirteen people suffered minor injuries and were transported to local hospitals. About 150 people were evacuated from the area because of broken natural gas and water lines. At the time of the derailment, the sky was overcast; there was no wind; and the temperature was 70° F. Estimated damages were $2.4 million.