None of the injuries at the Mesa Amphitheatre in Mesa, Ariz., was serious, according to Fire Battalion Deputy Chief Mary Cameli. Three of those treated were minors.

Most of the problems at the concert were heat-related, according to a venue spokesperson.

“The majority of the injuries that we had reported to us were not because of crushing or trampling,” Sherry Woodley told Pollstar. “We had one person with a health condition that was exacerbated by the heat. It had been 106 or 107 degrees, and in the bowl where heat gets trapped it can get as hot as 115 to 120 degrees.

“We were constantly supplying water and misting the crowds, but some people didn’t drink enough and got down there and became dizzy. And of course, once somebody goes down, there’s a chance for problems.”

A paramedic was also slightly injured after pulling someone from the crowd and was treated at the scene for minor injuries, Mesa Fire Battalion Chief Rod Lilly told The Arizona Republic.

The injuries happened as some of the crowd of about 4,000 fans pushed forward after No Doubt took the stage.