The powerful bomb that ripped off the face of a federal building in Oklahoma City on Wednesday very likely was made of inexpensive fertilizers and chemicals that are widely available at gardening centers, chemical supply houses and gasoline stations, civilian and federal explosives experts said.
Moreover, the ingredients can be mixed in a lethal brew by almost anyone, the experts said, guided by instructions that are published in hundreds of handbooks.
That information is also available on the Internet computer network and with equipment that is no more sophisticated than a kitchen blender.
Two teams of experts in bomb site investigations from the federal Bureau of Alcohol, Tobacco and Firearms were being flown to Oklahoma City to join FBI agents and local police in trying to determine precisely how the bomb had been made, planted and triggered.
But federal officials in Washington and Oklahoma said they suspect the bombers had packed 1,000 to 1,200 pounds of explosive material into a car or a van and had detonated it with either a simple timer, such as an alarm clock, or with a remote-controlled radio signal.
Judging from the extensive damage showing in television broadcasts of the building, Dr. Per-Anders Persson, director of the Center for Energetic Materials at the New Mexico Institute of Mining and Technology, said the bomb might have contained more than 2,000 pounds of explosives.
Because they are cheap and easy to make, fertilizer and chemical explosives are much more widely used in American industry today than dynamite and plastic materials, experts said.
For terrorists, fertilizer and chemicals are especially appealing because, unlike dynamite and plastics, their sale is not regulated.