Due to the detection of an unexploded bomb from World War II in the vicinity of the railway tracks, the Eurostar services connecting Paris and London were brought to a standstill on Friday. This incident also led to a domino effect of delays and cancellations affecting numerous other train services to and from the Gare du Nord, which is the busiest railway station in France.

Bright red signs warning of service disruptions greeted rail users at the usually busy Paris station, their travel plans thrown into disarray during the morning rush hour.

The repercussions quickly rippled beyond France’s borders.

In Brussels, trains to Paris were cancelled until at least Friday afternoon.

“There’s no solution, we’re going to call the hotel and stay one more day. And change our train ticket,” said Michel Garrot, a retired Parisian who was visiting the Belgian capital with his wife.

At London’s St. Pancras station, travelers who’d been looking forward to Paris’ charms found their plans dashed.

“We’re looking up flights, but our options are limited,” said Lauren Romeo-Smith, part of a group on their way to a birthday weekend.

Eurostar, which runs passenger trains through the Channel Tunnel between Britain and the continent, canceled all services between London and Paris for the rest of Friday and said passengers should travel on another day.

Passengers at St. Pancras were advised to take the train to Lille in northwest France, or fly to Paris.

Fridays are invariably busy at St. Pancras, Eurostar’s London hub, as thousands of people leave and arrive for weekend breaks on the continent.

French national rail operator SNCF says the Gare du Nord habitually sees 700,000 travelers per day, making it the busiest rail hub in both France and Europe.

As well as towns and cities across northern France and the Paris suburbs, the station also serves Paris’ main airport and international destinations including London, Brussels and cities in the Netherlands.

Bombs left over from World War I or World War II are regularly discovered around France but it is very rare to find them in such a people-packed location.

The SNCF said rail traffic was stopped at the request of police.

The bomb was discovered around 4 a.m. by workers doing earth-moving work near the tracks in the Seine-Saint-Denis region that borders Paris to the north.

Bomb disposal experts were sent to the site.

French Transport Minister Philippe Tabarot said traffic would be ‘’strongly disrupted’’ throughout the day with only limited service resuming in the afternoon, and urged travelers to postpone their trips.

Tabarot, speaking on broadcaster Sud Radio, said local residents and people near the train stations should have “no fear” of a risk of explosion, stressing the procedures in place for defusing and removing such bombs.