All at once, pandemonium broke loose. the marching band came around the corner, dogs began barking, and the horses pulling the mayor's carriage began to run! Which word best completes the passage above

Simultaneously.

Explanation:

All at once, pandemonium broke loose. Simultaneously, the marching band came around the corner, dogs began barking, the horses pulling the Mayors carriage began to run. This word maintains that all the occurrence happened at the same time.

can you explain it better