Data from the black box of EgyptAir flight MS 804 has showed that smoke alarms were sounded in the aircraft before it disappeared and crashed. Signs of soot and damage caused by high temperature were also found in wreckage recovered from the front part of the plane, Egypt’s civil aviation ministry said in a statement on Wednesday. However, investigators still do not know what caused the plane to crash.

The flight went missing on May 19 with 66 people on board before it crashed into the Mediterranean Sea. Investigators said the plane plummeted around 23,000 feet, and turned twice, before it went missing and was found in the sea. The aircraft flight recorder was also recovered from the Mediterranean Sea around two weeks ago, and contains recordings from the cockpit. Investigators have not ruled out that the flight could have been deliberately brought down.