The two engines on the Air India flight shut down within one second of each other before the Boeing 787 Dreamliner crashed last month in Ahmedabad, India, killing at least 260 people, according to a preliminary report released Friday.

The preliminary report on the Air India Boeing 787 crash indicates that a sudden and unexplained fuel cutoff to both engines was the immediate cause of the disaster. With no evidence of sabotage or technical defect so far, the focus remains on the cockpit actions and the design of the fuel control system.

Indian investigators determined the Boeing 787 Dreamliner was properly configured and lifted off normally. But three seconds after takeoff, the engines' fuel switches were cut off.