Pope Leo XIV was elected as the Catholic Church's 267th leader on Thursday.
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."
Tune in to "The American Pope: Leo XIV," a special edition of "20/20," streaming now on Hulu and Disney+.
White smoke was seen emanating from the chimney of the Sistine Chapel, indicating that a two-thirds vote has been reached to elect a new pope.
Thousands of people cheered in Vatican Square when the smoke appeared.
Vatican expert Mountain Butorac told ABC News that before a conclave begins, the chimney stack, which releases smoke alerting the public whether cardinals have elected a new pope, is stored in an attic in the Sistine Chapel.
Before the chimney was installed on May 2 on the roof of the Sistine Chapel, Butorac said it lived in the attic of the chapel, leaning against a wall.
Along with the cardinal electors, Butorac said other people working at the Vatican — those who press elevator buttons, drivers who take members of the clergy from Santa Marta to the Sistine Chapel and even the florist — are also required to take an oath to ensure the secrecy of the conclave.
Additional priests who are available to provide confession to cardinals during the conclave are also required to take the oath of secrecy, Butorac said.
Crowds are beginning to fill Vatican Square as the afternoon session of the second day of the conclave begins.
If on schedule, the voting cardinals should be back in the Sistine Chapel following their lunch break.
A third smoke signal is expected at 7 p.m. local time (1 p.m. ET). Black smoked emanated from the chimney on Thursday morning.
While all cardinals are summoned to the Vatican upon the pope’s death, only those under the age of 80 are eligible to participate in the conclave.
There are currently 252 cardinals worldwide. Of the total number of cardinals, 135 are age-eligible to serve in the conclave as cardinal electors, which is the largest number in history. Two electors told the Vatican that they would not be able to participate in the current conclave due to health reasons.
-ABC News’ Christopher Watson
