I think, with raspberry pi you can use one csi camera module.
What is with USB cameras? Perhaps you can use a USB hub to connect more than one camera via USB to the pi. I don’t know what you want to do with the images. But you have to consider that the cameras need processing power.
2017-04-27 11:30:26 UTC Tinkerberg - 4 points
since you have totally 4 USB2.0 ports on RaspberryPi 3, you can easily connect e.g. 3 Basler dart (board level) or Basler pulse (with housing) cameras:
For more information on e.g. fast saving of images on RasberryPi 3 refer to:
2017-04-27 11:30:17 UTC mbinev - 149 points
Use IP Webcam app in play store.
Connect 3 cameras and pi to a single wifi and then open IP webcam app in all of your phones. Each will give you a local host address which you can use in your browser in pi. Every phone will have different address so use address accordinly to access the particular camera. this set up is also wireless therefore easy to operate.
2017-08-21 06:33:14 UTC Shanque - 141 points