SAN DIEGO (AP) — A plane crash in San Diego that likely killed six people, including groundbreaking alternative music executive Dave Shapiro, happened as the private plane approached an airport whose runway lights were out in heavy fog, investigators said.

It could take a year to sort out exactly what happened to the plane that crashed into a neighborhood just before 4 a.m. Thursday. But investigators know there was thick fog, problems with the runway lights and a broken weather alert system, Dan Baker of the National Transportation Safety Board said.