Cuba is holding two days of national mourning for the victims of the plane crash at the main airport in Havana. An investigation has been launched over why the plane went down shortly after take-off. More than 100 people were killed in the ill-fated flight that was heading for a city in the island nation's east. Three survivors are fighting for their lives. CGTN's Giles Gibson reports from Havana.

An explosion rips through a quiet neighborhood on a Friday afternoon, a plume of smoke hanging over a green field. Local residents spotted the aircraft in trouble just before it plunged to the ground. 

YAIRI CASTRO RESIDENT "We were just leaving the house and we looked up and saw the plane turning as if the pilot was trying to maneuver the plane, I guess he was trying to find a place to crash land."

The video shows the chaotic scene in the minutes after the plane went down, Cuban authorities are now locking down the site.

GILES GIBSON HAVANA "I'm standing outside the airport terminal where the plane took off and this is the closest we can get to the actual crash site because the police have completely cordoned off the field where the plane went down. Everywhere around the crash site there are houses and businesses which narrowly avoided being hit by the plane."

This man made it to the field moments after the impact and did what he could to help - he'd just washed the blood off his arms and legs when we spoke to him.   

ALEXIS LORAS RIQUENES RESIDENT "There were burned people and children under the wreckage, there were many people trying to help even though the police tried to stop us from getting to the plane."

As investigators start to sift through the debris, Cuban authorities are launching an official investigation into the accident and announced two-days of national mourning for the crash victims on Saturday.

Meanwhile, 135 relatives are traveling to Havana from areas around Holguin to try to identify the bodies, but it could be many months before we know what caused Cuba's worst aviation disaster in three decades. Giles Gibson, CGTN, Havana.