How can I call a Angular component from a function inside a script tag inside index.html

I have this code below where I’m loading google maps API and I want to issue a callback when loaded to instantiate some other stuff in another component.
How can I call a component from this initMap()?

I tried adding this code below in my app.component.ts file in the ngOnInit method but it wasn’t called.

window[‘initMap’] = function() {…}

This code below is my index.html file for an Angular application.

// index.html
<script>
  function initMap() {
    // call component here
    console.log('test');
  }
</script>
<script src="https://maps.googleapis.com/maps/api/js?key=my-secret-key&libraries=places&callback=initMap" type="text/javascript"></script>