NEW YORK, A carbon monoxide leak in a building three blocks from the World Trade Center sickened 32 people and raised alarm that shuttered several busy blocks in lower Manhattan at the start of the workday Tuesday, authorities said.

The problem ultimately was traced to a broken boiler pipe in a grocery store basement, Fire Department Chief of Department James Leonard said. But people started feeling faint around 8:30 a.m. just as a worker opened a package in the basement, stirring worries that the parcel might have been poisonous.

The concern brought a police bomb squad and FBI agents to the scene. Authorities ultimately determined the package wasn't hazardous, Leonard said. It contained salad bowls.

"A prudent person could make that connection ? that 'the box opened, then we passed out.' But between the fire department and the police department, we ruled out that type of incident," he said.

The shop and the apartments above in the 12-floor building were evacuated as firefighters measured carbon monoxide levels that maxed out their meters in some places. The meters measure up to 1,000 parts per million, enough to "render you unconscious very, very quickly," Leonard said.

The normal level of carbon monoxide in a house can be from under zero to 15 ppm, depending on whether there's a gas stove, according to the U.S. Environmental Protection Agency.

While some people passed out in the store and its basement, all the injuries were relatively minor, Leonard said.

A person who answered the store's phone later Tuesday said no managers would be available to comment for the rest of the day.

Streets were cordoned off and emergency vehicles massed for several blocks around the building in the chic TriBeCa neighborhood. Small crowds clumped at police lines, tourists snapped photos and workers and residents tried to find out how to get where they were going.

The fire department's preliminary reports described the emergency as a basement fire, but officials later clarified that it was a leak.

Authorities began lifting the lines before noon.

-AP.