EXPOSITION PARK (CBSLA.com) — The 45th annual Special Olympics Summer Games Invitational began at the University of Southern California Friday.

The opening ceremony was held at 10 a.m. at Loker Stadium at USC, 3550 McClintock Ave., prior to the start of the games.

The three-day event will feature 1,200 athletes, 300 coaches, more than 2,000 volunteers, 1,000 local dignitaries, sponsors and many more spectators.

The athletes will compete in six sports: aquatics, athletics (track & field), basketball, bocce, golf and gymnastics. Summer Games Invitational is free to attend and open to the public.

The Special Olympics World Games organizing committee will be on hand all weekend to use the event as a test for various processes after Los Angeles won the bid in 2011 to host the World Games in 2015.

The committee wants to make sure the city is prepared to welcome more than 7,000 athletes from 170 countries in 25 sports for the world-class event.

The World Games will have a $415 million economic impact on LA County alone as it is expected to bring more than 30,000 volunteers and 500,000 spectators to the area.