How to make Python not to wait for the end of the command?

I am making a voice assistant and when I say "set alarm" program freezing and waiting for time that alarm set. So I can't talk to the assistant until alarm plays.
Here is the code

if 'alarm' in said:
    engine.say('Set')
    engine.runAndWait()
    now = datetime.datetime.now()
    alarm_time = datetime.datetime.combine(now.date(), datetime.time(int(said)))
    time.sleep((alarm_time - now).total_seconds())
    os.system("start alarm.mp3")

How to ignore it or make something to the program so it won't freeze? Maybe there are other ways for setting alarm?
Help will be appreciated!

You could create a thread that'll sleep for the specified amount of time. Sleeping threads don't block the main thread, so it'll continue executing.

import threading, time, os

def thread_func(seconds):
    time.sleep(seconds)
    os.system("start alarm.mp3")

threading.Thread(
    target=thread_func,
    args=((alarm_time - now).total_seconds(), ),
    daemon=True
).start()
# Do something else here

os.system will block the execution, but it should be fairly quick.