answered correctly by Raghuvansh, M S Srinivas, Amit Roy, Malcaluffin, Viswesh, Rithwik, Manish Achuth, Chitananda, Leo and Siddhart Jain
here is a video of the incident
Warning : It is very depressing to watch.
Some other facts.
Roger Williamson was 25, this was his second GP and his crash was caused by a tyre failure
David Purley was 28 during this incident. A couple of seasons later, he was involved in a massive accident where his car decelerated from 173 kmph to 0 in 66cm, the impact of 179.8 G’s is still considered to be the highest G force ever survived by a human. Purley never recovered enough to race in F1 again and was himself killed in 1985 when his aerobatic plane crashed into the sea of the coast of England.