Read the paragraph from The Hot Zone.At six-thirty, he gave an order to move out, and the column of vehicles left Fort Detrick's main gate and headed south, toward the Potomac River. It consisted of a line of ordinary automobiles—the officers' family cars, with the officers inside wearing civilian clothes, looking like commuters. The line of cars followed behind two unmarked military vehicles. One was a supply van and the other was a snow-white ambulance. It was an unmarked Level 4 biocontainment ambulance. Inside it there were an Army medical-evacuation team and a biocontainment pod known as a bubble stretcher. This was a combat medical stretcher enclosed by a biocontainment bubble made of clear plastic. If someone was bitten by a monkey, he would go into the bubble, and from there he would be transferred to the Slammer. The supply van was a white unmarked refrigerator truck. This was to hold dead monkeys and tubes of blood.