Officers of the Nigeria police force and some supporters of the PDP clashed at the party headquarters in Abuja on Thursday.
The protesters stormed the area as former Vice-President Atiku Abubakar submitted his presidential nomination form.
Atiku is one of the leading presidential candidates readying for the 2019 elections.
He was accompanied by Sen. Ben Bruce during the clash.
The police officers began to fire gunshots into the air to disperse the protesters.
The protesters were said to have mixed with Atiku supporters in order to enter the premises.