It is believed the blaze was sparked by a wayward firework which hit the roof of one of the terrace houses close to the Queen Vic pub.
Fire crews raced to the scene and quickly extinguished the flames before any real damage could be done.
Luckily, although the cast and crew had been filming live segments earlier on in the evening, no one was injured in the unfortunate incident.
This week, EastEnders is marking its 30th Anniversary with a host of special episodes, including a fully live show on Friday night.
More importantly, viewers are finally going to discover who killed Lucy Beale!
Speaking about last night's fire drama, an EastEnders spokesperson said: "There was a very small fire on set on Tuesday night after rehearsals had finished. It has not affected any #EELive week plans and nobody was harmed."
Ian Parkhouse, area fire commander for Borehamwood and Potters Bar, confirmed that crews were called to the scene at 11pm.
He added: "Thanks to the hard work of our firefighters, the fire was contained and extinguished before it could cause any serious damage to the set.
"We're pleased that we were able to deal with this incident quickly, so it shouldn't affect the 30-year celebrations taking place this week."
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