NEW HAVEN — An eventful graduation day at Yale University on Monday featured the awarding of degrees, dancing from Stevie Wonder, a union demonstration and a man who unexpectedly took the podium and was tackled.

Yale conferred more than 3,600 degrees, including eight honorary doctorates. The recipients of the honorary degrees included civil rights leader John Lewis, former Secretary of State John Kerry and musician Stevie Wonder.

Lewis, a Democratic Georgia congressman who was criticized by then-President-elect Donald Trump in a January tweet as "all talk," received a rousing ovation when he was introduced by Yale President Peter Salovey as a man with "a lifetime of bold action and inspiring results."

"From the Edmund Pettus Bridge in Selma, Alabama, to the halls of the U.S. Congress, you have been the conscience of our nation, guiding us on the unfinished march toward equality, civil rights and human dignity," Salovey said.

Wonder danced and sang along as the Yale University Concert Band played his hit "I Wish." He received an honorary doctorate of music from Salovey, who used Wonder's own lyrics to tell him the degree was "signed, sealed, delivered, it's yours."

The commencement was interrupted briefly when an unidentified man ran onto the stage during chaplain Sharon Kuglar's invocation and grabbed the microphone. He was able to get out a few words about loving Yale before being tackled by security.

Yale spokesman Tom Conroy said the man, who was taken into custody, is known to police and isn't believed to be part of any protest group.

More than 1,000 people marched across campus before the ceremony to demand the Ivy League school begin negotiations with a union that was formed by graduate students after the National Labor Relations Board lifted a ban on organizing teachers' assistants and researchers at private universities.

The school is appealing a ruling that allowed the union to set up microunits in eight Yale departments, arguing that that type of organization effort denied the majority of doctoral students the right to cast a ballot.

The protesters gathered near the gates to Old Campus and cheered as the graduates walked past on their way to the outdoor ceremony.