The government's emergency alert test took place yesterday (23 April), but unfortunately for those running the London Marathon, it caused slightly more disruption than expected.
Those finishing the gruelling 26.2-mile race could be seen looking at their phones at 15:00 GMT, as they attempted to turn the blaring alarm off.
With over 40,000 participants, there's no doubt some people will still have been trying to make the finish line as the alert played out, too.
The government insist the alert will only be used in emergency situations in future.
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