Seventy firefighters are attending a blaze at ZSL London Zoo.
London Fire Brigade (LFB) were called at 6.08am to the Adventure cafe and shop near the Meerkat enclosure.
Ten fire engines, and around 70 firefighters and officers are tackling the fire.
A photograph posted on Twitter by LFB shows smoke billowing from the building as firefighters work at the scene.
A spokeswoman for LFB said: "Approximately half of an adventure cafe and shop, which also contains an animal petting area, is currently alight.
"It is not believed any animals are involved at this stage."
She added that the cause of the fire is not currently known.