For 40 years, Los Angeles' building code has required all buildings 75 feet and taller to have a rooftop emergency helicopter landing facility in a location approved by the fire chief.

Wallers said the helicopter belonged to Air Angels Inc., an emergency medical transport service based at Clow Airport in suburban Bolingbrook.

It would be similar to a Humvee vehicle for patrolling on the ground but could turn into a helicopter at the touch of a button in an emergency.