The outage hit the Essential Energy's East Tamworth zone about 10.30am, leaving CBD businesses and some Tamworth schools and shopping centres without power.

Essential energy says 8000 customers were affected. 

It also took out power lights with police called in to direct traffic.

By 11am, power was progressively turned on across the city.

An Essential Energy spokeswoman told The Leader crews were working at the East substation to find out what the problem was.