A year after a deadly tornado ripped through Joplin, Missouri, killing hundreds, residents remembered the first anniversary with a sunrise service for medical workers and volunteers and survivors who were mobilized into action.

A four-mile unity walk through some of the city's hard-hit areas is also planned for later Tuesday, one day after President Barack Obama spoke at Joplin High School's graduation ceremony, where he praised the resiliency of residents for bringing the town, the nation and the world together to help rebuild the city from the rubble.

The tornado that touched down on the night of May 22, 2011 was the nation's deadliest in six decades, killing 161 people and leaving hundreds more injured. It damaged and destroyed thousands of homes, businesses and several schools, including the town's only public high school, Joplin High -- just hours after the Class of 2011's graduation ceremony.

The story of Joplin isn't just what happened that day, Obama said. It's the story of what happened the next day. And the day after that. And all the days and weeks and months that followed.

You'll remember that in a town of 50,000 people, nearly 50,000 more came in to help the weeks after the tornado -- perfect strangers who've never met you and didn't ask for anything in return, Obama added. Remember what people did here. And like that man who came all the way from Japan to Joplin, make sure in your own life that you pay it forward.

As part of the rebuilding process, Joplin is breaking ground on three new schools, according to the Associated Press.

Start the slideshow to see residents rebuild in Joplin.