The Oak Lawn tornado outbreak, 50 years later

OAK LAWN, Ill. (WLS) -- Fifty years after the deadliest tornado outbreak in the Chicago area, memories from that day still haunt survivors.

Dozens of people were killed on April 21, 1967. ABC 7 Meteorologist Phil Schwarz looks back at this moment in Chicago history.

Deadly tornadoes are not unknown to the Chicago area - Naplate, Fairdale, Utica and Plainfield all saw violent twisters in the last 30 years. But none of them compare to what happened in 1967.

Dottie Arnold was just in the second grade when the tornado struck, but has vivid memories of that day. She and her family rode out the storms safe in her basement, but were amazed by what they saw when they emerged.

"We went upstairs to see the devastation, it was quite breathtaking because the school that we attended was completely destroyed except for about one quarter of it," she said.

At least 10 tornadoes were reported that day, and three of them reached over F-4 levels with winds over 165 mph.

Oak Lawn, Lake Zurich and Belvidere all took direct hits in the afternoon hours as the commute was in full swing. Though the tornado was on the ground for 16 miles, some of the worst devastation occurred at the intersection of 95th and Southwest Highway. Of the 33 fatalities, 18 of them happened at that intersection.

Mary Lou Harker lives near that intersection.

"And all of a sudden she's screaming, like never before had I heard her scream like that. And she's going, 'Mommy! Mommy!' and she said she saw a desk flying in the air," she said.

Harker went down to the school where she found a badly injured boy who she rushed to the hospital and helped survive.

The Oak Lawn Library has put together a special display on the disaster, a very emotional task for historian Kevin Korst.

"He told the story of being in the doorway and seeing the tornado coming, and that's one of the stories that sticks out because he described what the tornado looked like. Then he went back into the restaurant, told people to get down, and was pinned under a walk-in freezer for about an hour," Korst said.

That man was among around 1,000 people injured that day. Fifty-eight people died in what remains the deadliest tornado outbreak in the history of the Chicago area.

Many of those who lived through the outbreak described the sky as turning green. While it is a common phenomenon when strong tornadoes hit, the exact reason behind it remains unknown.