SOUTH ELGIN (CBS/STMW) — One minute, they were working on Friday afternoon. The next, they were being led away on stretchers.

Several people were overcome by carbon monoxide inside a commercial building at 1200 St. Charles Road in South Elgin, with nearly 40 being sent to the hospital for treatment.

Paramedics rushed the 38 workers to area hospitals, sometimes four in one ambulance, CBS 2’s Pamela Jones reports.

Jeanne Hintz, owner of a company at the building that sorts products for manufacturers, says workers started getting sick around 2 p.m. Friday.

Firefighters say a couple of forklifts running in a business next door flooded the building with potentially deadly carbon monoxide. The level was almost 10 times what is considered acceptable. The multi-tenant building is known as the Elgin O’Hare Commerce Center.

Firefighters say the gas could have been building up all day. The business doesn’t have a carbon monoxide detector, and you can’t smell the gas.

Sherman Hospital in Elgin treated 12 of the sick workers. At least 5 were admitted, but all are expected to be OK.

Some workers returned Friday night to pick up purses and other items they had to leave at the time. They’re all grateful this bad situation didn’t become worse.

Victims were being taken to Delnor Community Hospital in Geneva, Sherman Hospital in Elgin, Saint Alexius Medical Center in Hoffman Estates, and Provena Saint Joseph Hospital in Elgin.

Federal officials are investigating the emergency.

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