Roman Catholic cardinals have held the first ballot in their conclave, but failed to elect a new pope.
As the first smoked emerged it was not clear if it was white or black
Black smoke billowed at 2005 (1805 GMT) from the chimney leading from the Sistine Chapel where the cardinals are holding their secret election meeting.
It signified that the 115 cardinals locked into chapel earlier on Monday had not reached a two-thirds majority.
Cheers went up from the more than 40,000 pilgrims gathered in St Peter's Square when the smoke emerged.
They had been congregating in the piazza throughout the evening, eager to witness the result of the first ballot to elect a successor to Pope John Paul II, who died on 2 April.
Bells to toll
The cardinals eligible to vote in the conclave will be shut off from the outside until they chose the man who will lead 1.1 billion Roman Catholics worldwide.
Up to four ballots will be held each day, and the ballot papers are burned after every second vote in a stove inside the Sistine Chapel.
Chemicals are added to colour the smoke - black smoke signals failure to agree on a candidate, while white smoke means a new pope has been chosen.
This time the white smoke will be accompanied by the ringing of the bells of St Peter's Basilica.
However, there was still some uncertainty about the colour of the smoke as it streamed out of the chimney.
"We thought it was white, then it went black. I had a feeling of exhilaration followed by disappointment," Harold Reeves, a 35-year-old theology student from the US, who was in St Peter's Square, told Associated Press.
115 cardinals take part
Two other eligible cardinals are too ill to attend
Must be aged under 80
Come from 52 countries
58 from Europe
Italy (20) and US (11)
0730: Cardinals celebrate Mass in hotel
0900: Morning voting starts
1600: Afternoon voting starts
1200 & 1900: Ballot papers burned, generating smoke
All times local (GMT+2)
"You can't describe the feeling. When the smoke came out it looked white and I got chills," an Italian student Silvia Mariano, added.
It had not been certain that the cardinals would even hold a ballot on the first day of the conclave.
Experts had predicted that even if they did so the chance of a pope being elected on the first ballot was extremely remote.
Earlier the cardinals processed to the Sistine Chapel from the Hall of Blessings in the Apostolic Palace.
As they entered the chapel, covered in Renaissance frescoes including Michelangelo's dramatic Last Judgement, they took their places at two rows of tables along the walls.
Before the door was closed, each of the cardinals swore an oath of secrecy and fidelity to the Church in Latin.
Afterwards the master of Vatican liturgical ceremonies, Archbishop Piero Marini, called out the words "Extra Omnes" ["Everyone Out"] - the order for all those not taking part in the secret conclave to leave.
The doors were then closed and the live television pictures ended.
Strict security measures have been imposed to ensure the secrecy of the conclave is kept.
Parts of the Vatican have been sealed off, and all staff who will come into contact with the cardinals have taken a vow not to divulge anything of what they see or hear.
Mobile phones, newspapers and television are banned, and the Sistine Chapel has been swept to check for bugging devices.
The cardinals will shuttle between the Domus Sanctae Marthae hotel - nestled within the city-state's walls, where they are staying - and the Sistine Chapel until the conclave is finished.