Alarm Triggered but system itself has not triggered for an alarm

My home system was disarmed at 5:30 a.m. At 11:40 a.m., an internal alarm went off, and my outdoor SimpliSafe camera siren went off, but the system did not trigger an event. Simplisafe monitoring was not notified, and my system control panel showed it was off. So why did the inside alarm and the camera siren go off for a good five minutes?