Several people have suffered broken bones including broken legs and broken ankles.
Officials say “several nationalities” are among those hurt. At this stage they are known to include a Romanian man, a Frenchman and a Belgian woman but it is not immediately clear if any Brits have been injured.
The incident happened around 2.30am this morning at a nightclub in a shopping centre in Adeje.
The incident is said to have occurred at the Butterfly Disco Pub, which describes itself on its webpage as a a gay club and says it is in Playa de Las Americas.
It opens from 11pm to 6am.
A website profile says: “The Butterfly nightclub has two larges spaces. In the main space you’ll hear the greatest gay hits.
“In the second room there is a stage where every night there is a show.”
Two of the casualties are said to have suffered “serious” broken femurs.
A spokesman for a local emergency services coordination centre said: “We received an alert that the floor of a disco had given way in an area of approximately four square metres.
“After collapsing, the people who were inside plunged about a floor’s height into the basement.”
Firefighters were mobilised to make sure no-one was trapped and eight ambulances sent to the scene.
The 22 injured have been taken to different hospitals.
The name of the nightclub has not been made public so far.
Adeje, near to Playa de Las Americas in the south of Tenerife, is a favourite of British holidaymakers.
This is a breaking news story. Please refresh the page for updates.
Additional reporting by Gerard Couzens