STORY: ::How the assassination attempt on Trump unfolded

Shortly after 6pm Saturday, Donald Trump takes the stage at his rally in Butler, Pennsylvania.

The Republican presidential candidate begins his campaign speech.

Minutes later, attendees notice a man on a nearby roof with a gun.

"He's got a gun"

Shots ring out.

Trump goes to the ground. Secret Service agents surround him with guns drawn.

A police sharpshooter on a roof behind Trump returns fire. The suspect is later pronounced dead.

Trump stands up with blood on his ear which is running down his face after getting shot.

He mouths "fight, fight, fight" with a fist in the air as the Secret Service rushes him to his car where he is taken to a local hospital and is treated and released.

Police say a rally-goer is killed and two others leave the scene in critical condition.

The shots appeared to come from outside the area secured by the Secret Service, the agency said.

It's raised questions about security lapses - and comes just four months before the November 5th election.