AAP supporters, who have assembled in large numbers, wanted to enter the site near the Rail Bhavan, but police refused entry to them, making the area out of bounds.
Following this, angry supporters crashed through the barricades and 200-300 supporters entered the protest site.
Incidents of stone pelting were reported, but police did not confirm this saying they have to verify the events.
Police said that with some 200-300 AAP volunteers entering the area near the Rail Bhavan, the crowd has swelled two to three times making the situation chaotic.
An AAP worker was injured and police was seen shifting him to the ambulance.
Senior Aam Aadmi Party (AAP) leader Sanjay Singh lashed out at the Delhi Police accusing them of brutally beating up a number of party workers.
"Police brutality is evident. Journalists were beaten up. A lot of our volunteers were beaten up.
"We are trying to maintain law and order and a lot of volunteers were injured and they are being taken to hospital," Singh, who is a member of the Political Affairs Committee (PAC), told reporters here.
He said the party was trying to ensure proper medical attention to all those injured.