Retired neurosurgeon Ben Carson on Monday announced his 2016 campaign for the White House with a kickoff event in his hometown of Detroit.

"I'm Ben Carson and I'm a candidate for president of the United States," Carson said.

The 63-year-old Carson, who has no political experience, rose to prominence in 2013 after he criticized President Obama during a National Prayer Breakfast as the president sat feet away. Though Carson ranks in the middle of the pack in early 2016 primary polls, he is considered an extreme long shot to capture the nomination.

Also Monday, former Hewlett-Packard CEO Carly Fiorina announced her candidacy for the 206 GOP nomination. The two join Sens. Ted Cruz (R-Texas), Rand Paul (R-Ky.), and Marco Rubio (R-Fla.) on the GOP side of the race.