In the women's 67-kilogram division, Hwang Kyung-seon defended the title she won at the Beijing Games. She previously won a bronze in Athens and becomes the first woman ever to win three Olympic taekwondo medals.
Hwang defeated Turkey's Nur Tatar 12-5 in a final in which both fighters attacked from the start. In the opening seconds, the two landed head kicks almost simultaneously. But Hwang soon took control, nailing Tatar with body and head shots.
Hwang dominated all her matches on Friday, using speed and flexibility to get an advantage on her opponents, often throwing several head kicks from the same leg before hitting her target.
She acknowledged there was pressure on the Korean team to bring home gold medals because the martial art was developed there. Until Hwang's win, only Lee Dae-hoon had managed a silver in the men's 58-kilogram division on Wednesday.
"It feels like flying," Hwang said after the match. "I've done something special for the country and it makes me very proud."
The bronze medals were won by Paige McPherson of the United States and Germany's Helena Fromm.
On the men's side, Sebastian Crismanich of Argentina won gold medal in the 80-kilogram division. He defeated Spain's Nicolas Garcia in a cautious final. Both seemed reluctant to attack and spent most of the match simply blocking each other's kicks.
Crismanich managed to land a body shot with eight seconds remaining and won 1-0. The 26-year-old Crismanich won the Pan-American championships last year. It is his first Olympic medal.
In most of his matches Friday, Crismanich was on the attack early, catching his opponents off guard with a rapid succession of body shots and head kicks.
Several top seeds made early exits, including five-time world champion American Steven Lopez, Iranian world champion Yousef Karami and top seed Ramin Azizov of Azerbaijan. Lopez's sister said on Twitter that Lopez had a broken leg.
The world No. 1, Britain's Aaron Cook, was conspicuously absent after he was not selected for the team. Cook said he felt cheated and was being punished for his decision to leave the national training program.
"I don't think I can ever move on from what they've done to me," Cook said.
Instead, British officials picked Lutalo Muhammad, ranked 109th. He won a bronze. Italy's Mauro Sarmiento won the other bronze, performing an impromptu victory dance where he swayed as if rocking a baby. He dedicated the medal to his daughter and then helped the man he had just defeated—an injured Nesar Bahawi of Afghanistan—off the mat.