Four people were picked up after they demonstrated at Bandar Mahkota, Cheras, due to road works being carried out at a traffic light junction leading to the area.
The demonstration which saw about 1,000 people, mostly residents from the nearby areas, gathering from 4pm to stop the work conducted by workers.
The protesting crowd played a cat-and-mouse game with the authorities until 10.30pm when the situation worsened.
Segambut MP Lim Lip Eng pulled the plug of a generator before standing in front of a water cannon to prevent the police from aiming it at the crowd.
Venting anger: Residents attempting to clear the concrete barriers situated at Bandar Mahkota Cheras yesterday.
During the ensuing commotion, Lim was said to have been assaulted .
It is learnt that Lim was rushed to the Kajang Hospital by Seri Kembangan state assemblyman Ean Yong Hean Wah and a friend.
Kajang OCPD Asst Comm Shakaruddin Che Mood said police resorted to firing the water cannons several times to ward off the protestors who were riding motorcycles and speeding towards the police barricades.
He said there were more than 100 policemen including personnel from the Light Strike Force and the Federal Reserve Unit at the scene.
The four arrested, aged between 20 and 30, were taken to the Kajang police station for questioning.
On Wednesday, a large group of residents from Bandar Mahkota and Sungai Long in Kajang gathered to protest against the closure of a road that leads to both housing areas.
The residents claimed that the action of the Cheras-Kajang Highway concessionaire, Grand Saga, to place concrete barriers at the road greatly inconvenienced them.
The closure of the road meant that residents had to pay toll and take a longer route to get to their homes.
Residents had demolished the barriers on April 21, two years after they were put up by Grand Saga, which has maintained that it had right of way over the road.
