BETHLEHEM, Pa. (AP) - Authorities are trying to find the source of a strong odor that prompted evacuation of several hundred people from an eastern Pennsylvania business park, sending 31 of them to hospitals.

Northampton County emergency officials said the problem at the Hanover Township building containing four businesses and a day care was reported shortly before noon Monday. Officials said at least 200 people were evacuated.Officials said 31 people who complained of nausea, vomiting and dizziness and were taken to hospitals for treatment.Township manager John Finnigan Jr. said air levels were deemed safe and there were no signs of a natural gas leak. People were allowed back into the building two hours later.Emergency crews checking gas lines found a small leak at a meter outside, but no measurable amounts inside.