London mayor Boris Johnson has described the actions of rioters who prevented firefighters from reaching burning buildings earlier this week as "demented".
Speaking as he visited Stoke Newington fire station in north-east London, he praised the "heroism" of crews who battled to extinguish blazes started by mobs across the capital.
London Fire Brigade received 2,220 calls - about 15 times the usual amount - on Monday night, and attended 1,500 incidents.
Mr Johnson said the challenge to firefighters during the riots had been "unprecedented".
He added: "London Fire Brigade was able to cope comfortably within its strength with the biggest fire challenge this city has faced for many, many, many years.
"I congratulate them on their management, on their organisation, on the dynamism of the men and women who serve, the firefighters.
"I think the firefighters have done the most incredible job and there are many heroes in the story of what has happened in the last few days, but London Fire Brigade is out here, at or near the top."
Some of the 49 staff at the station, who were among the first at the scene of the fires in Tottenham where the riots started on Saturday night, told the mayor how they came under attack themselves.
Mr Johnson said: "What strikes me as so barmy is just the idea that you could actually be at physical risk from people who are there on the scene.
"It's crazy, I mean what kind of mentality is that in people who attack firefighters. They are literally out of their skulls. They deserve very serious penalties in my view."