Customers on MARTA’s north-south line experienced delays early Thursday after customers pulled the emergency cords on the trains, the spokeswoman for the transit agency said.

In a Twitter post, officials initially said the delays were due to "police activity" at northbound West End.

MARTA spokeswoman Alisa Jackson later said “the behavior of these customers is the reason we are experiencing a temporary service delay.”

Normal service resumed just before 9 a.m.