Borehamwood's Elliotts sports and social club was destroyed by a massive blaze on Tuesday evening, which is being treated as arson.
It took around 50 firefighters, many drafted in from stations outside the area, two hours to bring the blaze under control, after they were alerted at around 6.50am.
Firefighters stayed at the smouldering scene all night, and continued to damp down hot spots the following day, when fire investigators and police forensic teams were also called in to investigate.
No-one was hurt in the blaze at the Rowley Lane club, owned by Marconi Transport Systems, which had been boarded up and was not used.
But Borehamwood Fire Station commander Danny Rickett criticised those who may have been responsible for putting their own and firefighters' lives at risk.
He said the blaze was fought from outside the building because of explosions, or flashovers, inside as temperatures soared to 1,000 degrees Celsius. The roof also collapsed.
He added: "Had our firefighters been in there when the flashover occurred, they would have been killed instantly because no one can survive 1,000 degrees Celsius.
"I am very concerned that if we get another of these fires, we are going to have tragic consequences."
The 80-metre by 20-metre pavilion, housed a social club, changing rooms and other facilities.
Police had to close surrounding roads to enable firefighters to tackle the blaze, and smoke poured onto the nearby A1.
Anyone with information is asked to call DS Andy Dixson on 01707 638223.
Figures released recently showed that the number of deliberate false alarms attended by Hertfordshire firefighters rose by 13 per cent last year. Nationally the number of hoax fires dropped by eight per cent. The number of house fires fell by two per cent, and the number of call-outs to automatic fire alarms fell by 12 per cent. Nine people died in Hertfordshire as a result of fires during 2000, three more than in 1999.
