Thousands of Nova Scotia Power customers in Halifax have their electricity back.

As 6:10 p.m., there were 21,324 customers on the Halifax peninsula affected by the outage, which snarled traffic during the afternoon rush hour.

Most of the outages were on the Halifax peninsula. (Nova Scotia Power)

According to Nova Scotia Power, the outage was a result of a transmission interruption at the Kempt Road substation. Crews were at the site Monday evening assessing the damage.

Power was restored around 6:30 p.m. Monday evening. Nova Scotia Power says the source of the problem was a "failed protective device" on a transformer.