They were protesting in capital Delhi while party president Sonia Gandhi was being questioned by a government agency that investigates financial crimes.
She and Rahul Gandhi have been accused of misusing party funds to acquire valuable real estate through a convoluted financial deal.
The Gandhis deny the allegations.
They have accused the governing Bharatiya Janata Party (BJP) of using federal law enforcement agencies for political vendetta.
This was the second time Mrs Gandhi was questioned in connection with the case.