Rafael Cervi was giving evidence at the "super inquest" into the deaths of six people who were killed in the blaze at Lakanal House, Camberwell in July 2009.
Rafael Cervi, whose wife and two children died, told the inquest he rushed back from work after being called by his wife to say fire had broken out in the block.
Mr Cervi said he watched the fire with his father-in-law Fernando Francisquini and initially reassured his wife that the flames did not look as if they were spreading to their flat.
The inquest into the deaths at the Lakanal House high rise block, in Camberwell, in 2009 has been long awaited by the families of Dayana Francisquini, Thais Francisquini, Felipe Francisquini-Cervi, Helen and Michelle Udoaka and Catherine Hickman.