The procession from Hoffmeister Colonial Mortuary on Chippewa Avenue to the Cathedral Basilica of Saint Louis began around 8:30 a.m.
People also gathered across the street and on nearby street corners to pay their respects to Langsdorf. Michael Flamion, a Ballwin officer who was shot and paralyzed on the job in 2016 - was spotted in the crowd.
Officers different law enforcement agencies lined up outside the Cathedral Basilica ahead of the funeral. Officers from Chicago, New York, Dallas and Fort Worth were among the many agencies in attendance.