The siren sound was emergency SOS, because you held a volume and power button too long.
Try a Forced Restart, which doesn't require touching the screen at all:
- Quickly press and release the volume up button
- Then immediately press and quickly the volume down button
- Then immediately press and KEEP HOLDING the side power button (keep holding and holding ever if you see the swipe to power off slider and keep holding until the screen goes black and keep holding until the Apple Logo appears - THEN LET GO
Hopefully, your phone will restart and normal operation resume, but if it does not, you'll need to take to the Genius Bar at your your Apple Store for evaluation and options.