Passengers on a southbound subway leaving King station Thursday morning were startled when the train doors opened inadvertently — the second such incident in less than a week.

The incident happened around 8:30 a.m. as the train was leaving the station. TTC spokesman Brad Ross said the train had received a red signal and stopped. That’s when a trainee operator, who was accompanied by an instructor, accidentally opened the doors.

“We’re not exactly sure why this happened,” Ross told CityNews.

Power was cut and the train was taken out of service at Union station, Ross added. The situation led to a nine-minute delay.

This latest incident comes just days after TTC CEO, Andy Byford issued an apology for a series of delays during Monday evening’s commute. On Monday night, the doors of a train stopped north of Dupont station inadvertently opened to the surprise of riders.

TTC chair Karen Stintz told CityNews that door opening was due to human error.

Last month, the TTC unveiled its first-ever customer charter, promising better communication with riders and increased punctuality, cleanliness and customer service.