On Halloween night in 1963, during a "Holiday on Ice" skating exhibition at the Indiana State Fairgrounds Coliseum, a propane gas explosion killed 74 people and injured nearly 400.

It was just after 11 p.m. With only three minutes remaining in the opening night show, the skaters were finishing a medley called "Mardi Gras." No one realized that propane gas was leaking from a rusty tank in the concession area, slowly filling the unventilated room.

As the skaters began gliding into a pinwheel formation for the finale, the gas came in contact with an electric popcorn machine. When the gas ignited, a blast of orange flame shot 40 feet up through the south-side seats, catapulting people and chairs through the air. Concrete chunks and body parts rained down. Many of the spectators fell on the ice on the south side of the arena, while others fell into a crater caused by the explosion and were buried underneath huge slabs of concrete.

Fifty-four people were killed on the scene and another 20 later died of their injuries.

'You walked into a nightmare'

Indianapolis News reporter Bill Roberts was attending the show with his wife. He described the scene in graphic detail:

For a few seconds, no one cried out. Then, there were screams and cries of agony and the audience jumped from their seats as if in unison and started rushing for the exits. The orchestra continued to play. My wife was drawn to a small blonde girl with her mother. The child's blue coat was soaked with blood. They were looking for the father. Outside the main entrance, a man was sitting with a huge black and blue lump by his left eye. Part of the calf of his left leg was gone.

Indianapolis Star reporter Richard R. Roberts reported the events as he saw them:

You walked into a nightmare. This was the worst thing I have seen since combat in World War II. The lights above still cast eh bluish light they cast onto the ice show. A red satin slipper lay on the ice. Three feet away was a pool of blood. A gray-haired man lay on his back staring lifelessly at the ceiling. Ambulance attendances threw a gray blanket across him. Chairs were scattered like ten-pins on the south end of the big building. The fairgrounds itself was almost like a battleground, the surrounding streets thick with police and the edges of the streets jammed with crowds like war refugees, slowing the movement of ambulances and fire engines.

The aftermath

Rescuers used the nearby cattle barn as a temporary hospital, and the coroner's office set up a temporary morgue on the ice floor.

The dead were placed on plywood and lined up on the ice according to gender and age. Family members who came to identify loved ones had to register at the administration building before being led to the Coliseum. Every hospital in Indianapolis and surrounding counties took in the wounded. Medical and nursing students were utilized.

Twenty women sat in a basement room of the Red Cross chapter house at 1126 N. Meridian St. answering nearly as many phones. They spent hours telling callers where the injured were, verifying fatalities or accepting offers of aid and blood donations. One volunteer delivered the news to Marine Cpl. Melvin Deubner on duty in Vietnam that his mother Margaret Evans had been killed in the explosion.

A Marion County grand jury indicted the state fire marshal, the Indianapolis fire chief, the general manager and the concessions manager of the Coliseum, as well as officers of the company that supplied the gas. But there was only one conviction, the president of the gas supplier, and that verdict was later overturned by the Indiana Supreme Court. According to the Encyclopedia of Indianapolis, victims and survivors ultimately received about $4.6 million in settlements.

In 1991, the Coliseum acquired a sponsorship and was renamed Pepsi Coliseum; however, that sponsorship was not renewed in 2012. It is now known as the Indiana Farmers Coliseum. The Coliseum underwent a $63 million renovation, which was completed in 2014.

Follow IndyStar Visuals Manager and RetroIndy writer Dawn Mitchell on Twitter: @dawn_mitchell61.