View Full Version : Handling an outdoor bomb threat

10-26-2012, 09:17 PM
I'm writing a story with the premise built around a bomb threat phoned into the police. The target is supposed to be a group gathering outdoors in a large park. I understand that sometimes bombs can be rigged to explode on receiving a radio or cell phone signal. So my question is how would the police work around this possibility to coordinate their efforts while minimizing risks to the public? Would they have an emergency communication system that's unlikely to set off such a bomb as a precaution? And if it's possible to jam cell phone signals to avoid accidentally setting off the bomb, can they coordinate their work around that? I'm assuming they'll have resources either on-site or off-site that can track the location of someone calling in a threat, and would want to communicate that and other information. Thanks!

10-26-2012, 09:44 PM
First, most public places would never be secure enough to prevent radio or cell communications. All emergency systems rely on radio transmission but, with a valid threat, radios could be turned off.

Bombs rigged to a cell phone or radio trigger, such as a garage door open, are standard in IED's around the world. But it's a specific signal. Military units do jam these signals, most civilian agencies would not have the technology.

The first priority in a bomb threat is to clear the area of potential casualties. Then the robots, dogs and bomb squad are sent in. A bomb specifically set to injure people in an open area would be shrapnel-based, like a pipe bomb with nails or ball bearings. These are ridiculously easy to construct and the information is easily available on the internet.

Everything depends on how sophisticated your bomber is, what his intentions are and what resources he has available.


10-26-2012, 10:25 PM
Thanks, WeaselFire. A couple of beta readers also questioned whether the first priority would be clearing the area or determining whether the threat was credible.

That would presumably be related to how to get people to clear the area, who maybe don't want to leave, without creating panic. There's often a caution against yelling "fire" when there's a fire, right?

And if the responders have to communicate, I don't want to create a problem in logic by having them use cell phones or tablets to communicate when they're concerned similar devices might trigger an explosion. Could that be worked around by using a specific signal (frequency?) for their communication?

I certainly don't want the story to come across as implausible.

Robots, huh? That might be a cool element to introduce.

10-26-2012, 11:25 PM
Most bombs rigged to go off by cell phone mean that a cell is used to call to trigger it, not that any cell used in the vicinity will trigger it.

Also yes, it's about whether it seems credible, clearing the area, sweeping the area.

10-30-2012, 12:12 AM
I'm a police dispatcher, credential wise.

When we get bomb threats its up to the venue, building, manager, of the place that's been threatened to decide if the threat is credible. I'm sure that a sufficiently large gathering would draw the attention of the ATF or FBI, and they have their own way of doing things.

While I've not had in-depth contact with the bomb squad, I can say we have a huge range of radio frequencies to work with, so it's unlikely the bomber would set it to off from a known police band frequency unless they had a way of preventing a touch-off once they activate the bomb. I mean to say, they set the bomb to a common frequency and turn it on. Within a minute that bomb explodes, because at least where I work, most channels stay busy.

If they treat the bomb-threat as credible, they're going to evacuate the area and call in bomb-sniffing dogs and the bomb squad to look for suspicious devices/objects.

When we handle a bomb threat in dispatch, it's always handled by phone. We don't want the bomber listening to whether or not the officers are there on a scanner.

Any other questions that are more specific, I'll be happy to try and answer.

10-30-2012, 06:31 AM
If they jammed communication frequencies it would be with the intent of stopping the bomber from detonating the device, rather than trying to avoid accidental detonation. As someone mentioned, the signal will be fairly specific and an accidental detonation unlikely. There was a jammer called the Warlock (google warlock, IED jammer), which was mounted on a humvee. I assume large police departments would have something similar.

10-30-2012, 10:27 AM
Thanks, cornflake, Bookislovakia, and espresso5! Your replies are very timely. I've got to wrap this story up within a couple days, and I think I've now got a more credible way of addressing beta reader concerns.

Bookislovakia, are (cell?) phones the way of handling communications in the field in situations like this? I ran across a mention or two of some special communication system for emergency responders, sounded like it might be associated with a device resembling a Blackberry or tablet, from what I could tell. I'll try to find the name of it again.

espresso5, one of my questions had to do with whether jammers might be an option. Some information on the Internet suggests they're available (in terms of technology), but that they might interfere with police communications, and that there are also questions related to legality of their use even by authorities. Additional thoughts on that?

Also wondering about wording that might be recommended to clear an outdoor area without causing panic.

10-30-2012, 01:38 PM

I couldn't tell you 100% since my involvement with the bomb squad is tertiary, but I know we get them started by cell phone and they go from there on their own. Again, to prevent the bomber from listening in on a scanner.

When they or the SWAT team get out there, they have their own dispatcher with special, specific radio frequencies they use for dispatching, and hand signals and so on. I doubt I can be more specific without talking to a bomb squad member, and then, they may be reluctant to do so!

I'm pretty sure when we clear an area we just tell people there's been a bomb threat, please remain calm, and we'll lead you out of the area to safety. Officers will drive up without lights and sirens close to the venue so as to keep the atmosphere calm. When uniforms show up and act calmly and professionally, generally everyone will follow that lead.

EDIT: We get bomb threats on a regular basis at the local university, for instance, and I can't think of a time when we've had a panic clearing out the building.

10-30-2012, 08:05 PM

espresso5, one of my questions had to do with whether jammers might be an option. Some information on the Internet suggests they're available (in terms of technology), but that they might interfere with police communications, and that there are also questions related to legality of their use even by authorities. Additional thoughts on that?


I was embedded with the Iraqi Army and we didn't use the jammers because, while it didn't interfere with our communications, it would interfere with the Iraqi communications, but at the time they were using basic Motorola walkie talkies. If a police department had a jammer, they would probably use radios not affected by it. Here's a wiki article. The references might have more specific info.

10-31-2012, 01:08 AM
Thanks again, Bookislovakia and espresso5! Exactly the types of details I was wondering about and couldn't figure out.

On to wrapping up that story!