Investigators have seized an AR-15 rifle following the assassination attempt on former US president Donald Trump at a campaign rally in Pennsylvania on Saturday, according to media reports. The weapon is believed to have been used in the shooting, the New York Times and Washington Post reported. Trump escaped with a light wound to his ear, but one man was killed and two others suffered serious injuries in the incident in the small town of Butler, north of Pittsburgh. The AR-15 is a semi-automatic rifle mainly produced by arms manufacturer Colt. The gun is almost identical in appearance to the …