Hoax bomb

A bomb threat is generally defined as a threat, usually verbal or written, to detonate an explosive or incendiary device to cause property damage, death, or injuries, whether or not such a device actually exists.

Criminal statutes typically dictate severe penalties. For example, in the United States, Massachusetts provides for penalties of up to 20 years in prison, up to $50,000 fine, and restitution for the costs of the disruption.New York law makes it an "Class E Felony ... to issue a false bomb threat directed toward a school in New York State."

Some statutory definitions include the threatened use, release or placement of other harmful agents, such as poisons, biological pathogens, radioactive materials, or even a dangerous weapon (e.g., aboard an airliner). Other statutes enhance the penalties for threats made against specific places or persons (e.g. government facilities or dignitaries), and the actual possession of harmful devices or agents.

Many bomb threats that are not pranks are made as parts of other crimes, such as extortion, arson, or aircraft hijacking. Actual bombings for malicious destruction of property, terrorism, or murder are often perpetrated without warning.

The decision to evacuate an area or building, depending on the perceived reliability of the threat, may be made by local controlling authorities or those in charge of the targeted facility based on advice from bomb disposal experts. When a large facility is involved, it can be very difficult and time-consuming to ensure the absence of any bomb or other hazardous device or substance.

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Wikipedia