Pope Leo XIV will be the Catholic Church's 267th leader.
VATICAN CITY -- The temporary chimney atop the Sistine Chapel released a plume of white smoke on Thursday evening local time, signaling that the 133 cardinals working inside had reached a two-thirds majority to elect a new pope for the Catholic Church.
American Cardinal Robert Prevost was shortly thereafter announced as the 267th pontiff. He chose the name Leo XIV, a senior cardinal deacon announced.
The 69-year-old Chicago native is the first American pope and is seen as a diplomat in the church.
"This is the first greeting of the risen Christ. May the peace be with you," Leo said in Italian in his first remarks as pope. "This is the peace of the risen Christ."
(The Associated Press and ABC News contributed to this report.)
Pope Leo XIV - history-making, the first American Pope. Now, David Muir reports from the Vatican in the breaking, new "20/20" special edition. Watch the premiere of "The American Pope | Leo XIV" tonight at 9/8c on ABC. Stream on Hulu and Disney+
The master of ceremonies has called "extra omnes" -- ordering all those who are not cardinal electors to exit the Sistine Chapel prior to the start of the conclave.
The door to the Sistine Chapel closed as the cardinals begin the process of choosing the new pope.
The conclave starting Wednesday is the most diverse in history, with cardinals coming from all over the world to elect the next pope.
The majority of the cardinals are coming from Europe, including 17 electors from Italy, five from Spain and five from France.
There are 16 cardinal electors from North America, including 10 from the United States. Additionally, there are four from Central America, 17 from South America, 18 from Africa, 23 from Asia and four from Oceania.
Argentina, the home country of Pope Francis, has four cardinal electors.
The 133 voting cardinals have taken the oath of secrecy prior to the official start of the papal conclave, meaning they will be without modern technology for the days-long voting process to elect the next leader of the Catholic Church.
Since recording technology of any kind is forbidden during the conclave, the cardinals' cellphones have been taken away.
The phones will not be returned until the new pope is elected.
Technicians also ensured that there are no secretly installed bugs or similar devices inside the Sistine Chapel or adjacent areas.
The 133 cardinals line up to take an oath to ensure the secrecy of the conclave to elect the next leader of the Roman Catholic Church. Each cardinal will place their hand on the Book of the Gospels to take the oath.
The oath promises to keep the secrecy of anything that relates to the election of the new pope.
