The affected sectors get their power supply from the 66KV grid station in Mohali, about 10km from Chandigarh.
"The disruption was caused by a technical problem at the Mohali grid station, which is now being repaired," said MP Singh, superintendent engineer of the Chandigarh Electricity Department.
Residents of Chandigarh, the capital of Punjab and Haryana, complained that officials failed to give them any information on the outage.
"The officials were not able to inform us as to when the (power) supply would be restored. We had to come outside our houses. Even street lights were not working," JN Sharma, President of the New Light Housing Society in Sector 51, told IANS.
The supply was restored in some sectors at around 12.30 AM. However, the problem of low voltage persisted in many areas till 9 AM on June 21.