Participants in Donald Trump’s rally in Arizona reported suffering mysterious eye problems as a result of the event.

At the rally on September 12 in Tucson, Arizona, which was attended by more than 2,000 people in heat of over 38 degrees, numerous Trump supporters had to be taken to the emergency room.

The Trump campaign has said it is investigating the incident. The Secret Service told News 4 Tucson it was not aware of anything unusual at the rally, adding that it was not aware of any planned threats to Trump in Arizona.

Newsweek The Trump team asked for comment via email.

The rally was set up so that 48 exclusive participants could stand on stage with Trump. They were then divided into two groups, one on the right side of the stage and one on the left side of the stage.

The group on the left of the stage reported no symptoms or anything else suspicious, but according to a report from News 4 Tucson, several people in the group on the right of the stage left the rally with unbearable pain in their eyes.

Mayra Rodriguez, a former Planned Parenthood director and now Trump supporter, told News 4 Tucson that her eyes were burning and she could barely see. She said she went to the emergency room, where she was asked if she had been sprayed with anything.

She told reporters that she was still in pain days later. She said: “I can’t see anything. When I try to open my eyes, it’s like a white cloud covering me. It hurts.”

Newsweek has asked Rodriguez for comment via email.

Another woman, who wished to remain anonymous, reported the same symptoms and said, “This is horrible.”

And a man who also wished to remain anonymous said: “My eyes were red as hell, it was horrible, I just couldn’t stand it.”

Kathleen Winn, a former congressional candidate from Arizona’s 6th Congressional District, told News 4 Tucson after the incident: “We hope there are no nefarious actors involved here and that this is not a strategic attack.”

Newsweek has asked Winn for comment via email.

At the rally itself, Trump spoke about two policy proposals: first, the abolition of a tax on tips and, second, making housing “affordable again.”

At the rally, Trump announced a new tax plan and promised to abolish overtime taxes.

The Harris campaign was in Tucson the same day. Harris and her husband, Doug Emhoff, hosted a well-attended but private event in downtown Tucson.

Both candidates are expected to spend a lot of time in Arizona, as it is a key swing state with 11 deciding votes in the Electoral College.

In addition, Arizonans carry the legacy of John McCain, and Jimmy McCain’s recent support of Harris could sway undecided Republican and independent voters.

According to the most recent Arizona poll conducted by Data Orbital on September 17, the candidates are neck and neck at 46 percent. However, the average of all recent Arizona polls puts Trump ahead by a narrow 0.8 percent.

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