Mumbai, Oct. 12 -- As Mumbai's power supply is restored in phases and emergency backups kick in, a majority of the services have started resuming. The unexpected power outage in Mumbai caught telecom infrastructure off guard, with around 10% towers likely impacted immediately after the power cut, according to industry sources.

The power supply failure was caused by "technical problems" during maintenance work, the energy minister of Maharashtra said in a video message. Power has now been restored to many areas of the city, officials and witnesses said.

Telecom subscribers took to social media to raise concerns about the lack of telecom and data services across the city and affected regions.

"The severe grid electricity outage in Mumbai...