With at least 71 killed, Monday night’s tragic plane crash in the Colombian Andes is one of the worst aviation disasters in the nation’s history. To understand what caused Brazil and the Chapecoense team aboard to suffer such unthinkable loss, officials are now turning their attention to determining how the fatal accident occurred.

Before the chartered aircraft went off of radar, it had declared an emergency, according to Colombia’s aviation authority Aerocivil. The plane, which was traveling from Santa Cruz, Bolivia, to José María Córdova International Airport in Rionegro not far from Medellín, reported an electrical failure to the control tower.

Officials recovered the “black box” voice and flight recorder from the crash site yesterday. An investigation is already underway into that data and whether the tragedy was the result of electrical failure, weather, human error, some combination of those factors, or something else entirely.

Speculation has surfaced that the plane may have ran out of fuel. With standard fuel tanks, the range for the aircraft, an Avro RJ85 short-haul jet built by British Aerospace and operated by Bolivian charter company LaMia, is not not much greater than the distance between Santa Cruz and Rionegro.

It is believed that the Chapecoense flight had entered a holding pattern prior to falling off the radar. It is not known exactly why the plane entered a holding pattern, as shown in video of the flight route recorded by FlightRadar24.

The weather during Colombia’s current rainy season has been abnormally volatile and violent over the past month, creating major delays and even airport shutdowns across the country. After the crash, emergency officials were forced to cancel a helicopter-based search and rescue due to fog and rain conditions, and even the ground-based operations were halted later in the morning due to a downpour.

Another plane also made an unexpected landing at José María Córdova airport around the same time that the Avro RJ85 was nearing its destination. A VivaColombia flight that had left Bogotá for the Colombian island of San Andres in the Caribbean had requested an unplanned stop at the airport, and some have questioned whether that flight was given priority by the control tower.

If the plane carrying the Chapecoense football team was stretching its fuel range and forced to remain in the air longer than expected, running out of gas could have led to engine failure and electrical problems, according to aviation experts interviewed by Fox News. The outlet also noted that flight plans generally include sufficient fuel for unexpected delays or rerouting to a different airport than the expected destination if necessary.

For now, this all remains speculation. As authorities analyze the flight recorder data today and potentially are able to talk with the flight crew members who survived, more should soon become known about what exactly caused the plane to crash.