An underground transformer fire is caused power and traffic issues in Center City on Wednesday morning. Firefighters were called around 6:30 a.m. for a report of an underground transformer fire at SEPTA’s Walnut-Locust Station, near 16th and Walnut Streets. It knocked out power to 130 customers and caused some traffic issues in the area of 16th and Walnut Streets. As of noon, only six customers remain without power. The fire is now out. The cause remains under investigation.