This footage shows a small woman at a gym attempting to lift a massive 400-lb barbell in front of her daughter, but the device appears to be too heavy and it falls onto her, crushing her neck onto the bench and killing her on the spot.

The person she was at the gym with, reportedly her daughter, and other gym goers immediately rushed to help her after the 180-kilogramme (397-lb) barbell fell on the back of her neck, leaving her slumping to the floor lifeless. One man can be seen lying her on her side as they all look on in apparent shock.

The incident took place at a Gym Fitness Sport gymnasium located in the neighbourhood of Peralvillo in the borough of Cuauhtemoc in the Mexican capital Mexico City on Monday, 21st February.

The woman, who has not been named but who was reportedly between 35 and 40 years old, was exercising at the gym, reportedly with her unnamed daughter, when the tragic incident occurred.

The footage shows a burly man adjusting the weights on the device before the woman positions herself to lift it. But it all goes horribly wrong, and the bar immediately hits the back of her neck, pinning her down.

The man and the young girl try to lift the barbell off the woman to free her, but their attempts are in vain. Two other people then come over and help lift the device, with the woman then slumping lifeless on the floor.

The woman’s daughter was reportedly very affected by the incident and is believed to be receiving psychological support.

The state prosecutor’s office has opened an investigation into the incident.

The owner of the gym, who has not been named, was reportedly briefly arrested in order to confirm the woman’s identity.

The investigation is ongoing.