Questions remain about planning and crowd control after Friday's deadly concert in Houston

Authorities in Houston are investigating what went wrong at an outdoor concert Friday night that left eight people dead and dozens of others injured.

The crowd of some 50,000 people surged the stage, crushing and trampling people while Travis Scott was performing on stage at the Astroworld music festival in Houston.

Here & Now's Scott Tong talks to Steven Adelman, vice president of the Event Safety Alliance, about what went wrong Friday and how to make crowded events safe.