Earlier, at around 5:30 PM on October 21st, fishermen discovered a bomb approximately 200 meters downstream from pillar number 9 of the Long Bien Bridge and reported it to the authorities.

Immediately after receiving the report, the Long Bien District Military Command took measures to move the bomb closer to the shore, and at the same time mobilized militia forces from Ngoc Lam and Bo De wards to guard and ensure the safety of the site.