An explosion Tuesday afternoon inside a Park Ridge dry cleaners shattered windows and injured two people working inside.

The blast originated from a piece of dry-cleaning equipment in the rear of Holt Cleaners, 29 S. Fairview Ave., about 1:30 p.m., said Deputy Fire Chief Jeff Sorensen.

Park Ridge firefighters investigate an explosion that blew out the front and rear windows of Holt Cleaners. (Jennifer Johnson/Staff Writer)

The explosion, which was heard blocks away, shattered the building's large front windows, as well as two smaller windows in the back. As of Tuesday evening, firefighters were still investigating the exact cause of the explosion and whether natural gas or an equipment malfunction was to blame, Sorensen said. A language barrier also hampered the department's attempts to interview employees at the scene, he said.

Gino Rago, of Panino's Pizzeria next door, said he and his brother, Lenny, ran to the cleaners after hearing the explosion. They saw flames coming from the back of the building, and one man's hair was on fire, Gino Rago said.

After the brothers told other employees to get out of the building, Lenny Rago retrieved a fire extinguisher and used it to put out the fire in the man's hair and extinguish the flames coming from the nearby equipment, his brother said.

When firefighters arrived, the fire had been completely extinguished, Sorensen said.

The man who caught fire was transported to Advocate Lutheran General Hospital, as was a female employee. Their conditions were not immediately known, but their injuries are not life-threatening, Sorensen said.

Sara Brunetti and Deana Rago, also of Panino's Pizzeria, said the explosion sounded like a plane crashing on top of their roof.

"That's how loud it was," Rago said.

About 20 people were inside the restaurant -- which just held its grand opening Monday -- and all immediately ran outside, Brunetti said.

Gail Haller, executive director of the Park Ridge Chamber of Commerce, which is less than a block north of the cleaners, initially thought the loud noise she heard came from the water-main construction taking place in front of her Main Street office.

"Then I heard the sirens -- and they didn't stop," she said.

While some clothes sustained damage -- a pile of what appeared to be ruined men's pants lay near the rear door -- most of the clothing dropped off for dry cleaning was untouched, Sorensen said.