A blood pressure device being used as a prop on the set of the soap opera "Guiding Light" (search) broke apart Thursday just before the taping of an emergency room scene, and a small amount of mercury spilled onto the stage floor.

"Our staged emergency turned into a real life emergency," executive producer Ellen Wheeler said.

No immediate injuries were reported, but elevated levels of the toxic substance were found in the air, city Department of Environmental Protection spokesman Ian Michaels said. The CBS (search) studio, at 222 E. 44th St. in Manhattan, was to be closed for at least 24 hours.

The prop cracked when it was dropped by a scene designer, producers said.

Michaels said that by the time the DEP arrived, "they had tried to clean it up with a brush and a piece of cardboard or something and they had put the mercury into a jar," which he called "the wrong thing to do."

A hazardous-materials crew from the Fire Department of New York was called to the studio and tested the air and the soles of people's shoes, FDNY spokesman Jim Long said.

"The worst was that someone stepped in it and went into another room," he said.

Cast members, many dressed as doctors or nurses, and crew members were held for testing, then cleared to leave. The DEP ordered a 24-hour evacuation to clear the air "because the real potential for harm is in breathing the mercury," Michaels said.

DEP testers said they will check the site Friday before the show can go on.

The show was issued orders to properly dispose of the mercury and the brush and makeshift dustpan, which would probably mean a licensed cleanup crew would be hired, Michaels said.

"We think that given 24 hours the air level will come down, and as long as the disposal is done properly there should be no ill effects," he said.

He noted, however, that mercury poisoning works slowly and said anyone who was exposed should see a doctor if he or she feels ill.

Mercury is a poisonous metal that can damage a person's brain, nervous system and kidneys. Exposure can cause tremors, irritability and memory loss.

A statement from Procter & Gamble Productions Inc., which produces the show, said that in the scenes that were about to be taped, "a guilty Tammy pledges devotion to an unconscious Sandy despite her lustful feelings for her cousin Jonathan."