At water leak closed O’Hare Airport L station Thursday morning, forcing the CTA to run shuttle buses from Rosemont to the aiport, the transit agency said.

The O’Hare terminal closed at 8:55 a.m. after a water leak was detected in one of the terminals, CTA spokeswoman Catherine Hosinski said, citing preliminary information.

The Chicago Fire Department is assessing the situation, she said.

Blue Line trains are being turned around at Rosemont, and a shuttle bus is operating in both directions between Rosemont and O’Hare, Hosinski said.

Hosinski said the problem “appears to be an O’Hare issue.” A spokesperson for the city’s Department of Aviation could not immediately be reached for comment.

It is not yet known how long Blue Line service will be suspended.