An investigation got under way Wednesday to determine why a twin-engine airplane crash-landed at the Oceanside Municipal Airport. Two people aboard the Cessna were not injured in the crash-landing, which occurred at 8:35 p.m. Tuesday, according to the Oceanside Fire Department. The plane came to rest off the runway, about halfway down the strip, and about 30 gallons of fuel from the plane's tanks spilled onto some dirt, OFD Battalion Chief Bob Cotton said. Firefighters contained the spill and sprayed the Cessna with foam, he said, adding the plane was later moved to an area east of the airport. The Federal Aviation Administration was notified and is investigating the incident.