CHICAGO -- A marking on an expressway underpass is creating a stir in Chicago.

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Slideshow: People Flock To See Supposed Image Of Virgin Mary

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Obdulia Delgado said she was driving home along Fullerton Avenue on April 10 after getting off work at St. Elizabeth Hospital when she saw the Virgin Mary on the wall. She quickly pulled over and examined the form, and then began praying.

Delgado said she rushed home and told her husband, Fidel, what she saw.

Fidel Delgado said he was skeptical of his wife's claim until the two went to the site.

"I was just stunned," Fidel Delgado said at the underpass Monday morning.

Late last week, the couple, who live near the site, met with their priest from St. Francis of Assisi Church Obdulia Delgado said.

The priest told the Delgado couple that the image should be seen as a positive aspect of their lives, even though other people might be skeptical or poke fun at their claim.

After meeting with the priest, the two felt determined to spread the word of the image and late Sunday around 100 people gathered and knelt in prayer to see for themselves, Obdulia Delgado said.

Some people are taking pictures, inscribing their names and leaving flowers at the scene, but Satanic messages have also been left, NBC station WMAQ reported.

"It's a miracle. It's an image of something ... you can't describe it," Jose Recinos said.

Road specialists believe the marking may have been caused by salt or a water mark from expressway above, WMAQ reported.