The accident happened Monday evening at the Lancaster fairgrounds, about 90 miles north of the state capital in Concord. 250 people were in the tent when it collapsed, according police. The National Weather Service had issued a severe thunderstorm watch for the area before the time of the collapse. Sarasota, Fla.-based Walker International Events was scheduled to do two shows Monday. An investigation is ongoing. At this time is not known yet if any safety rules were broken. The company had not yet a public reaction after the accident.Gov. Maggie Hassan said state officials are monitoring the situation. Such repeated similar accidents in bad weather condition possibly urge to issue some rules for public events organizers.