Donald Trump Shooting Live Updates: Nearly 2,500 delegates are gathering in Milwaukee this week for a roll call vote to select the Republican presidential nominee, with a vast majority of them bound to support former US president Donald Trump. Trump had clinched a majority of convention delegates on March 12, but he doesn't officially become the party's standard-bearer until after the roll call. However, due to state party rules, at least a handful are slated to go to former candidate Nikki Haley, even after she released her delegates. Trump sustained injuries after he was shot at a Pennsylvania rally on Saturday. One rally attendee was killed and two other spectators were also injured in the shooting. The gunman, a 20-year-old, was killed shortly after. The FBI has identified the shooter as Thomas Matthew Crooks of Pennsylvania. The police are assessing the motive of the attack. In his first remarks on the attack, Trump appealed for national resilience, saying it was "more important than ever that we stand United". Senior advisers of Trump's campaign also said that he was in "great spirits" and "doing well", in a memo accessed by AP. Who is responsible for Trump's security? Republican lawmakers have said that they would investigate how a person managed to evade Secret Service agents and climb onto the roof of a building during the election rally, and fire multiple shots, news agency Reuters reported. The attack will certainly lead to a review of Trump's security, and he will likely be provided with a level of protection more akin to a sitting president, a former Secret Service agent told Reuters. During most of Trump's election campaign spots, local police aid the Secret Service in securing the venue, along with agents from other bodies within the Department of Homeland Security.