An underground fuel tank has exploded in Sydney's north-west, shattering the windows of several buildings surrounding the site.

Inspector Norman Buckley, from Fire and Rescue NSW, said the gas explosion occurred about 12.30pm on Blaxland Road, near the intersection with First Avenue, in Eastwood.

Two men were taken to hospital for minor facial injuries, while a further seven people were assessed at the scene by paramedics.

A number of workmen were attempting to remove an underground fuel tank when the explosion occurred, Inspector Buckley said.