Emergency services are at the scene of a large explosion which occurred on the Slough Trading Estate around 10:00.
The force of the blast was so big that some witnesses nearby thought it was an earthquake.
Berkshire fire and rescue say they are battling a blaze at a plastics and chemical plant.
Crews were called to the Duco International plant which provides printing and varnishing services for metals and plastics.
A spokeswoman for Thames Valley Police said [...] it was thought to have been a chemical explosion but it was unclear if anybody had been injured.
More than 30 firefighters are at the scene tackling the fire.
The 462-acre (1,869,648 sq m) business park was made famous as the location for the BBC television comedy series The Office, though the building affected is not that shown in the programme's opening credits.