Google has released an opensource framework built on top of Tensorflow, called the Tensorflow Object Detection API which is a tool for making it easy to make and deploy object detection models.
There are different state of the art types of models you can build. It you for instance make models using the Single Shot Multibox Detector (SSD) with MobileNets you will get lightweight models that you can run in real time on mobile devices.
The models you get are Single Shot Multiboc Detector, using MobileNets or Inception V2, RegionBased Fully Convolutional Networks with Resnet 101, and Faster RCMM with Resnet 101 or Inception Resnet v2.
You also get a Jupyter notebook for trying things out
If all these terms above makes no sense, you can read this excellent blog post explaining Deep Learning for Object Detection by Joyce Xu.