President Obama and leaders from around the world are attending a memorial for former South African president Nelson Mandela at a soccer stadium in Johannesburg. Obama will give one of the eulogies.

At least 23 members of Congress are headed to South Africa for the event, which was scheduled to begin at 4 a.m. EST (11 a.,m. in South Africa). The start of the ceremony was delayed, however, as world leaders and ordinary South Africans continued to arrive.

Mandela, a Nobel Peace Prize laureate and anti-apartheid activist, passed away Thursday at the age of 95.