What should you do if a person suddenly makes strange sound and falls to the ground unconscious lying stiffly on their back for few seconds before beginning jerk arms legs?

1. Stay calm and assess the situation. Make sure the area is safe and that there are no immediate dangers.

2. Call for help immediately. Dial 911 or your local emergency number.

3. Check the person's airway. Make sure the person's airway is clear and that they are breathing.

4. Start CPR if necessary. If the person is not breathing, start CPR immediately.

5. Monitor the person's condition. Stay with the person and monitor their condition until help arrives.

6. Provide support. Reassure the person and let them know that help is on the way.

7. Follow the instructions of the medical professionals. When they arrive, follow the instructions of the medical professionals.

Additional information:

* The person may be having a seizure. Seizures are caused by abnormal electrical activity in the brain. They can vary in severity and duration.

* Seizures can be frightening to witness, but they are usually not life-threatening.

* If the person is having a seizure, it is important to stay calm and not panic.

* Do not try to restrain the person or put anything in their mouth.

* Once the seizure is over, the person may be confused or disoriented. Stay with them and help them to calm down.