Seoul, South Korea (CNN) -- It was code-named "Dawn of Gulf of Aden," and when South Korea gave it a green light Friday, its daring execution led to five hours of chilling drama on the high seas.
A South Korean navy destroyer and Lynx helicopters fired warning shots as elite forces, in pre-dawn darkness, silently approached the deck of the freighter Samho Jewelry, hijacked by Somali pirates Saturday, according to the Yonhap news agency.
The pirates fired with their AK-47s and rocket-propelled grenades. The South Koreans shot back.
When it was all over, the South Koreans had rescued 21 sailors, killed eight pirates and captured five others, said Lt. Gen. Lee Sung-ho, a spokesman for South Korea's Joint Chiefs of Staff.
The captain of the 11,500-ton ship was shot in the stomach during the rescue, but no other crew member was hurt.
South Korean President Lee Myung-bak praised the bold rescue in a nationally televised address. "Our military carried out the operation perfectly under difficult circumstances," he said. "We will not accept any actions that threaten the lives of our people."
Lee said the U.S. military also assisted in the operation.
A U.S. Navy helicopter from the USS Shoup performed a medical evacuation in the operation.
"This mission shows that the South Korean government will not negotiate with pirates," Lee said.
The South Koreans launched their secret rescue mission earlier in the week, chasing the Samho Jewelry for days in the Arabian Sea. When the pirates seemed exhausted and after intelligence that suggested a pirate "mother ship" was leaving a Somali port, the South Koreans decided to attempt the rescue, Yonhap said.
The Samho Jewelry was carrying chemicals from the United Arab Emirates to Sri Lanka when it was hijacked.
Somali pirates have seized seven other South Korean ships. All but one have been released with ransom payments, Yonhap said.
CNN's Paula Hancocks and Charley Keyes contributed to this report.