Safety officials in New Hampshire are investigating the collapse of a circus tent during a severe storm that killed a father and daughter and injured about 22 others.

"We all this morning have heavy hearts," Gov. Maggie Hassan told WMUR-TV early Tuesday. "We lost two lives -- a father and a daughter -- at an event that was supposed to be fun."

Authorities were looking at how the tent was put up at the Lancaster Fairgrounds, about 90 miles north of the capital of Concord. They also were talking to survivors and witnesses.

Heidi Medeiros, who was at the circus with her 3-year-old son, said it suddenly went dark and she heard someone screaming, "Get out, get out."

"I see these very large metal poles that are in the ground and go through the top of the tent, I see them starting to come out of the ground and fly up, into the air toward us," she told WMUR-TV. She said 10 to 30 seconds later, the pole slammed onto the bleacher where she and her son had been sitting.

Fire Marshal William Degnan said it was the first time his agency had investigated a tent collapse. He asked that anyone with images or video of the event to contact his office.

The storm, packing 60 mph wind gusts and hail, blew through around 5:30 p.m. Monday, just as the first of two scheduled shows was beginning.

Degnan said about 100 people were inside the tent at the time, and a man and a girl died. Their names were not released. The injured were taken to four regional hospitals. Their conditions were not immediately known.

The circus operator, Sarasota, Florida-based Walker International Events, did not return a call seeking comment late Monday. The circus was scheduled to head to Bradford, Vermont, for shows on Tuesday and Wednesday.

The National Weather Service had issued a severe thunderstorm watch for the area during the time of the collapse, but Degnan couldn't immediately say if the spectators were aware of the storm's strength.

The collapse comes a day after one man died and more than a dozen were injured when a tent where people had sought shelter during a brief storm blew off its moorings and fell on some of the crowd at a festival in a Chicago suburb. The annual celebration known as the Prairie Fest had attracted about 5,000 people when the tent collapsed.

The popular Lollapalooza music festival in Chicago's Grant Park briefly shut down Sunday afternoon due to the weather, then resumed less than an hour later. Organizers ended the final day of the festival 30 minutes early Sunday night when another storm hit the area.