Emergency services are tackling a fire involving a commercial building off Micheldever Road in Whitchurch.
A large number of emergency service crews are currently at the scene, with significant amounts of smoke reported in the area.
Road closures have been put in place while firefighters deal with the incident, and people are being advised to avoid the area where possible.
Motorists travelling on nearby roads are also being urged to take extra care, as smoke could affect visibility.
Residents living close to the incident are advised to keep doors and windows closed while the fire is being dealt with.