MOSCOW — Russian investigators looking into the fiery crash landing of an Aeroflot jet in Moscow, an accident that killed at least 40 people in full view of hundreds at the country’s main airport, were focusing Monday on pilot error, equipment failure and bad weather as possible causes.

After the plane skidded to a stop on Sunday at Sheremetyevo International Airport, Russian news media reported that some passengers had insisted on grabbing their carry-on bags before leaving the burning wreckage — a violation of basic emergency protocol that would have slowed the evacuation. Videos posted online showed people walking away from the jet with luggage.

As the scale of the disaster emerged, many Russians reacted with outrage at the initial, soothing reports on state media and in a statement from the airline that had suggested that all aboard had survived the jet fuel inferno.

The Aeroflot flight took off from Moscow on Sunday evening bound for Murmansk, a port city in northern Russia. Pilots signaled distress soon after takeoff, the news agency Interfax reported, and the plane circled back for an emergency landing.