Hersman said investigators watched airport surveillance video Monday to determine whether an emergency vehicle hit one of the students. But they have not reached any firm conclusions. A coroner said he would need at least two weeks to rule in the matter.
Thirty-seven patients remain hospitalized at San Francisco area hospitals with eight still in critical condition.
Asiana Airlines Flight 214 was carrying 291 passengers and 16 crew members when it crashed. The tail was torn off as it crashed, and it burst into flames. More than 180 people were initially taken to local hospitals for treatment.