Multiple people were arrested as former US president Joe Biden made a surprise visit to Trinity College in Dublin on Tuesday.

Biden, 83, was accompanied by former first lady Jill Biden to a ceremony where their son, Hunter Biden, accepted the Gold Medal for Outstanding Contribution for Public Discourse.

Demonstrators and spectators assembled outside the venue during the event hosted by the College Historical Society (HIST). As Biden departed, some people stepped forward and threw objects.

Gardaí public order unit officers and vans were stationed at the site and arrested at least two people.

Aside from the ceremony, the former US president also met with Taoiseach Micheál Martin.

Months after leaving office, Joe Biden revealed that he’d been diagnosed with prostate cancer.

He is set to release a new memoir this month and said Sunday that he “won’t be able to do as many conversations about my book as I’d hoped” due to his health.

He said his doctors “continue to be encouraged by how I’ve responded to treatment” while acknowledging, “some days are better than others. It hasn’t stopped me. But sometimes it slows me down.”

Promise Me, America, is set for a Nov. 17 release.