Actor and writer Tim Downie, who lives around 600 metres from the scene in Latimer Road, said he feared the block could collapse.
He said: “It’s horrendous. The whole building is engulfed in flames. It’s gone. It’s just a matter of time before this building collapses.”
Fire chiefs said a structural engineer is monitoring the stability of the building, which “continues to be safe for our crews to go and work in”.