An Asiana Airlines 777 from Seoul, Korea crash-landed at San Francisco International Airport last night. Two were killed, ten were critically injured, 181 others were taken to hospital.
This Reddit thread contains a lot of great, breaking information, including audio from the SFO air traffic control during and after the crash, and eyewitness accounts from SFO and from diverted fliers who were landed elsewhere (SFO is closed until further notice).
It's not clear what caused the crash. Forbes has some early analysis of the debris field based on aerial photos. A prominent theory cited in several news reports is that the tail of the 777 caught the seawall and ripped free (this also suggests that the two fatalities were flight attendants in the rear jumpseats). Update: An Asiana Airlines rep has confirmed that the two dead were passengers; specifically, teenagers from China. Read the rest