A fire in a large commercial building in Cromwell, in Central Otago, has been extinguished overnight.

Fire crews were sent to the blaze at freight and rubbish collection company CromTrans just before 4pm yesterday.

At its height, eight crews were battling the blaze and and extra water tankers were brought in.

A Fire and Emergency spokesperson said the fire was put out about 10pm.

Two fire investigators were on the site last night and it is expected crews will return to do checks this morning.

The cause of the fire is not yet known.