Thousands of passengers departing London’s Heathrow airport were forced to fly without larger items of luggage on Thursday morning after the baggage-handling system serving two of its terminals broke down.

British Airways flights were worst hit, with the failure afflicting the carrier’s Terminal 5 base, as well as Terminal 3, used mainly by BA, American Airlines and their allies in the Oneworld group, as well as Virgin Atlantic Airways Ltd. and Dubai-based Emirates.

Services departing Europe’s busiest hub between 6:45 a.m. and 9 a.m. were affected by the breakdown, before baggage-drop desks were reopened, Heathrow said in a statement. More than 60 flights took off from the two terminals during that period, according to the airport’s website.

“We recommend that passengers who have already departed on flights this morning without their baggage contact their airline for further updates,” Heathrow advised, after previously recommending that travelers on affected services transfer essential items to their hand luggage, which they were permitted to carry aboard.

Heathrow apologized for the breakdown, without saying what had caused it. The failure comes weeks after a power outage at a British Airways data center led hundreds of flights to be scrapped over three days, grounding at least 75,000 passengers. BA parent company IAG SA, has said an engineer inadvertently disconnected a cable, leading information-technology systems to crash.

The carrier said after the baggage-system breakdown that it’s doing everything it can to reunite customers with their luggage as soon as possible.