American teenager Virginia Thrasher won the first gold medal of the Rio 2016 Olympic Games, holding her nerve against two Chinese Olympic champions to clinch the women's 10m air rifle event.
The 19-year-old US college champion, competing in her first Olympics, edged out China's Du Li, who won gold in Athens in 2004, with an Olympic-record score of 208 in the sport's new finals format.
The Olympics got off to a shambolic start on Saturday with fans queuing for hours to enter the stadium and some spectators missing their events as many athletes competed in front of eerily empty stands.
Games organisers apologised for dropping the ball on the first day of full competition, the morning after a dazzling opening ceremony, as iconic venues such as beach volleyball on the famed Copacabana beach saw only a few hundred spectators.
Outside, lines stretched for several blocks as angry fans stood in the scorching sun, waiting as security staff struggled to cope.
Handball matches also saw far from full stands as did the hockey tournament.
Defending Olympic champion Yi Siling, also of China, took the bronze medal.
The youngest of the eight finalists by several years, Thrasher established an early lead after battling with the Russian shooter Daria Vdovina, who stumbled midway through the competition and finished fifth.
Elsewhere, Brazil's male beach volleyball pair Alison Cerutti and Bruno Schmidt made a winning start in their hunt for gold, beating their Canadian opponents in straight sets on Copacabana's golden sand.
Both games were close, but Brazil's gold medal favourites fed on a festive, partisan crowd to defeat Josh Binstock and Samuel Schachter 2-0.
Later, security officials on Saturday said they were investigating reports that a bullet tore through a tent in the media area of the equestrian centre in the Deodoro area of the Olympic park in Rio de Janeiro.
"Security is investigating that incident and will make a statement later," the venue manager Anja Krabbe told Reuters news agency.
Earlier, the sound of a loud blast shook the media seats near the finishing line of the men's cycling road race when Brazil's bomb squad carried out a controlled detonation on an unattended backpack.
A witness reported seeing bomb squad agents in protective clothing operating near the area where media were seated on the boulevard of Copacabana beach. That followed the controlled detonation of another unattended bag near the same spot on Friday evening during the opening ceremony for the Games.
A spokeswoman for the public security department said officials believe the bag may have belonged to a homeless man, but protocol requires that any unattended objects be destroyed.
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The 2016 Olympics in Rio de Janeiro were officially opened with a flamboyant ceremony celebrating Brazil’s history and cultural diversity on Friday night.
Marathon runner Vanderlei Cordeiro, who was denied victory at the 2004 Athens Games when he was attacked by a spectator, lit the iconic cauldron.
Protests marred the lead-up to the opening ceremony but Al Jazeera's Latin America editor Lucia Newman said the mood in Rio had completely changed.
"What a difference a day makes," she said.
"Yesterday, Copacabana was full of protesters and people were very angry about the Olympics, and at the interim president. But now, after they saw the opening ceremony, they were moved and very, very proud.
"They seem to be warming up a bit to the Olympics."