A truck possibly hitting a powerpole on McPherson street has been blamed for a power outage that left thousands of Horsham residents without power on Tuesday night.

A Powercor spokeswoman said crews found a fallen high voltage line when they attended the site.

"Crews repaired the line and were able to progressively restore power to customers throughout the evening , with power back on to all customers by 1.07am," she said.

"Thank you to those customers who did contact us to report this incident as it assisted our crews to locate the fault and restore power more quickly."

There was no traffic control at intersections in the CBD during the blackout, with Horsham Police saying drivers managed well enough without help.

​UPDATE, 10pm Tuesday:

POWER has been restored to more than 1000 customers, however more than 1300 customers in the Horsham are still without power.

Powercor has listed the cause of the power outage as "vehicle impact" on Dooen Road, Horsham.

A second power outage at Henry Street, Horsham is listed as "under investigation".

Restoration is for remaining affected customers by 11.30pm.

Previously:

HORSHAM is experiencing a blackout Tuesday evening, with power expected to be restored by 11.30pm the same night.

Power went out in sections of the town about 8.30pm, and Powercor has listed the outage as 'still under investigation.'

A Powercor spokesman said that 3219 customers are currently without supply.

"It happened 25 minutes ago. I do know we're working on it and estimated time for restoration is 11.30pm and it will hopefully be earlier than that," he said.

More to come.