Due to overcrowding at the dais, a portion of it caved in and many RJD workers fell down, eyewitnesses and the police said.
Prasad later addressed the public meeting at the same venue, about 12 km from Arwal town. Prasad came to address the election meeting in support of RJD candidate from Arwal Ravindra Singh when the mishap took place.
Nobody suffered any major injury in the mishap, Station House Officer of Town Police station Kanhiah Singh said.
The RJD chief later jokingly said, "Nothing bad happens to good person like me, but those who have committed some wrong are punished."
Prasad has been on a whirlwind tour of the state addressing on an average 7-8 election meetings to drum up support for grand secular alliance in the Bihar elections.