At 4:56 a.m., central daylight time, on October 15, 2005, westbound Union Pacific Railroad (UP) train ZYCLD 13 2 collided with the rear of standing UP train MPBHG 15 in the UP rail yard in Texarkana, Arkansas. The collision resulted in the puncture of a railroad tank car containing propylene, a compressed flammable gas. The propylene was heavier than air and flowed near the ground into a nearby neighborhood. The flowing gas reached a house where an unknown ignition source ignited the gas, and the house exploded. The single occupant was killed. The fire moved quickly along the flowing gas back to the punctured tank car. A second, unoccupied, home was destroyed in the fire, and a wooden railroad trestle burned completely. Approximately 3,000 residents within a 1-mile radius of the punctured tank car were advised to evacuate the area. The two crews and the employees working at the Texarkana yard were not injured, and they evacuated the area safely. Between 5:00 a.m. and 7:00 a.m., the wind was calm, the visibility was 10 miles, and the temperature was approximately 59° F. Total damage was $2.4 million, including $325,975 in equipment damage and $2,053,198 in track damage.