San Francisco Fire Department Chief Joanne Hayes-White said the two who died were found outside of the plane. "Having surveyed that area, we're lucky that there hasn't been a greater loss," she said.
Airport spokesman Doug Yakel said 49 people were critically injured and 132 had less significant injuries.
South Korean government said the passengers included 141 Chinese, 77 South Koreans, 61 Americans, three Canadians, three from India, one Japanese, one Vietnamese and one from France, while the nationalities of the remaining three haven't been confirmed.
Chinese state media identified the dead as two 16-year-old girls from China's eastern Zhejiang province. China Central Television cited a fax from Asiana Airlines to the Jiangshan city government. They were identified as Ye Mengyuan and Wang Linjia.
At least 70 Chinese students and teachers were on the plane heading to summer camps, according to education authorities in China.
Asiana President Yoon Young-doo said at a televised news conference that it will take time to determine the cause of the crash. But when asked about the possibility of engine or mechanical problems, he said he doesn't believe they could have been the cause.
He said the plane was bought in 2006 but didn't provide further details. Asiana officials later said the plane was also built that year.
Yoon also bowed and offered an apology, "I am bowing my head and extending my deep apology" to the passengers, their families and the South Korean people over the crash, he said.
Four pilots were aboard the plane and they rotated on a two-person shift during the flight, according to the Ministry of Land, Infrastructure and Transport in South Korea. The two who piloted the plane at the time of crash were Lee Jeong-min and Lee Gang-guk.
Yoon, the Asiana president, described the pilots as "skilled," saying three had logged more than 10,000 hours each of flight time. He said the fourth had put in almost that much time, but officials later corrected that to say the fourth had logged nearly 5,000 hours. All four are South Koreans.