The yellow line linking Montreal to Île Ste-Hélène was shut down Friday afternoon shortly after 3:30 p.m., due to a police intervention outside the Jean-Drapeau metro station.
According to Montreal police (SPVM), officers on patrol found a suspicious package near the Biosphere.
A security perimeter was established and the SWAT team was called in.
In a tweet, the SPVM announced the package had been neutralized.
The incident happened as thousands of tourists and race car enthusiasts were on the island for Grand Prix festivities.
Service on the yellow line, between Berri-UQAM and Longueuil, was back to normal by 4 p.m.
Officers continued to search the area to ensure no other packages were found.
Around 4:30 p.m., the SPVM said the operation was over and no explosives were found.