Router is not defined

Router is not exported as a property of ‘react-router’ anymore and this construction is not valid cause Router is ‘undefined’

import { Router, Route } from 'react-router'

render((
  <Router>
    <Route path="/" component={ App }>
      <Route path="page1" component={ Page1 }/>
      <Route path="page2" component={ Page2 }/>
      <Route path="page3" component={ Page3 }/>
    </Route>
  </Router>
), document.getElementById('app-container'));

What is the new way to use react-router? Thank you!