BUTLER, Pennsylvania (Reuters) - Donald Trump was standing on a stage behind a podium, six minutes into his speech at an outdoor rally in Butler, Pennsylvania, his head turned to the right, under a clear sky and in broiling heat.

Suddenly there was a volley of "pops" - what sounded like gunshots. Trump immediately clutched his right ear, looked at the blood on his hand and then quickly dropped to the ground behind the podium.

The crowd screamed and many crouched.

A half dozen Secret Service agents ran onto the stage and piled on and around Trump, who was lying behind the podium. Other law enforcement officers armed with rifles also took to the stage.

There was a second volley of apparent gunshots.

The Secret Service agents kept Trump on the ground for 25 seconds. Someone could be heard shouting: "Shooter is down!"

Someone else yelled: "Move!" as many in the crowd continued to scream.

The agents raised Trump to his feet, his red "Make America Great Again" baseball cap no longer on his head, his hair disheveled, his ear bloodied and streaks of blood smeared on his face.

"Let me get my shoes. Let me get my shoes", Trump said, as the agents lifted him from the ground. He then said: "Wait, wait, wait", before he started pumping his fist.

One agent raised his arm above Trump's head, to shield it from more potential shots.

Trump continued to pump his fist towards the crowd, mouthing "fight." Many in the crowd began chanting "USA, USA".

As the Secret Service agents surrounded Trump and moved him to a nearby black SUV, Trump continuously raised his fist as they pushed him into the vehicle, to more chants of "USA!"

All attendees at Trump rallies have to go through Secret Service bag checks and electronic monitors to check for weapons before they are admitted to his rallies.

"I heard about four shots and I saw the crowd go down and then Trump ducked also real quick. Then the Secret Service all jumped and protected him as soon as they could. We are talking within a second they were all protecting him," Ron Moose, a Trump supporter who was in the crowd, told Reuters.

Moose said he saw a man running and being chased by law enforcement officers. He said he heard additional shots, but did not know who fired them. He said that by then law enforcement snipers had set up on the roof of a warehouse behind the stage.

Two women in their seventies sitting near the stage told Reuters they saw two people go down in the bleachers after the shooting and police tending to them.

The two women said they saw police rush to apprehend one man.

(Reporting by Nathan Layne; Writing by Tim Reid; Editing by Ross Colvin and Daniel Wallis)

By Nathan Layne