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(NewsNation) — Moments before shots were fired at former President Donald Trump during a campaign rally, witnesses say they saw the suspected shooter climbing to the roof of a nearby building.

Easton Smith, who was outside of the security perimeter at the rally, claimed he saw a man making his way up, saying, “Didn’t know what he was doing.”

He and others in the area were “trying to alert cops and police there was a guy crawling on the roof,” when they noticed the rifle he carried.

“After that, a couple shots fired off,” Easton Smith told NewsNation affiliate WKBN/WYFX/WYTV.

Those couple of shots grazed Trump’s ear, according to the president’s message on Truth Social. The attack, which killed one attendee and gravely injured two more, is the most serious attempt to assassinate a president or presidential candidate since Ronald Reagan in 1981.

Another witness, named Greg Smith, told BBC News the suspected shooter had crawled on top of the building located just outside the event. He said he pointed the gunman out to police.

“I’m thinking to myself, ‘Why is Trump still speaking, why have they not pulled him off the stage’… the next thing you know, five shots ring out.”

Smith was listening from outside the rally and said he saw the gunman around five minutes into Trump’s speech.

“We noticed the guy bear-crawling up the roof of the building beside us, 50 feet away,” he said. “He had a rifle; we could clearly see a rifle.”

“We’re pointing at him, the police are down there running around on the ground, we’re, like, ‘Hey man, there’s a guy on the roof with a rifle’… and the police did not know what was going on.”

Smith said he tried to alert the authorities for three to four minutes, but thought they probably could not see the gunman because of the slope of the roof.

“Why is there not Secret Service on all of these roofs here?” he asked. “This is not a big place. (It’s a) security failure, 100% security failure.”

NewsNation’s Damita Menezes and The Associated Press contributed to this report.