The discovery of a misfire World War II bomb near the truck put the Eurostar service between Paris and London on Friday, allowing other trains to cascade scores with Gare du Nord, France's busiest train station.
Bright red sign service disruption warnings usually greet train users at busy Paris stations, their travel plans were confused during morning rush hour.
The impact quickly spread across the French border.
In Brussels, trains to Paris have been cancelled until at least Friday afternoon.
“There's no solution. I'll call the hotel and stay another day. I'll change my train ticket,” said Michel Garrott, a retired Parisian, who was visiting the Belgian capital with his wife.
At St. Pancras Station in London, travelers looking forward to the charm of Paris discovered their plans had been shattered.
“We're looking for flights, but our options are limited,” said Lauren Romeo Smith, part of a group on the way to their birthday weekend.
Eurostar, which operates passenger trains traveling through the channel tunnel between the UK and the continent, has cancelled all services between London and Paris for the rest of Friday, saying passengers should travel on another day.
Saint Pancras passengers were encouraged to take a train to Lille in northwest France or fly to Paris.
On Friday, thousands of people arrive on a weekend break on the continent, St Pancras, the London hub of Eurostar.
French national rail operator SNCF says Gare du Nord has a habitual look at 700,000 travelers per day, making it the busiest railway hub in both France and Europe.
In addition to towns and cities in northern France and the outskirts of Paris, the station also serves major airports in Paris and international destinations such as London, Brussels and cities in the Netherlands.
Bombs left behind from World War I and World War II are regularly discovered around France, but they are very rarely found in places filled with such people.
The SNCF said rail traffic was stopped at the request of police.
The bomb was discovered around 4am by workers working to move the earth near the tracks in the Seine Sendennis region, adjacent to the north of Paris.
Bomb disposal experts have been sent to the site.
French Transport Minister Philip Tabarott said that limited services will resume in the afternoon, urging travelers to postpone travel, and that traffic will be “strongly confused” throughout the day.
Speaking on the station's SUD radio, Tabarot said local residents and people near the railway station should not “fear” the risk of explosions, and emphasized the steps to eliminate and remove such bombs.
