Dela Rosa, former President Rodrigo Duterte supporters gather outside Senate building

Supporters of Sen. Ronald "Bato" dela Rosa and former President Rodrigo Duterte gathered at the front gate of the Senate building on Monday evening, Katrina Son reported on "State of the Nation."

The supporters said that what happened to Duterte more than a year ago is also happening to Dela Rosa. They also questioned why is this done to fellow Filipinos and that due process should be followed.

Earlier, supporters quarreled with National Bureau of Investigation (NBI) Director Melvin Matibag, before the latter was allowed to enter the Senate premises.

The NBI proceeded to check the vehicles leaving the compound. One vehicle, which was believed to belong to former Senate President Vicente "Tito" Sotto III was chased by supporters.

Former congressman Mike Defensor was at the site on Monday evening and encouraged members of a "wage coalition" to go to the Senate compound to conduct a peaceful protest for the Senate and for Dela Rosa.

Katrina Son also reported that as of 9:50 p.m. the NBI personnel have left the compound while the protest action is ongoing.

National Bureau of Investigation (NBI) personnel earlier arrived at the Senate to serve an arrest warrant related to the investigation of the International Criminal Court's (ICC) investigation into killings that linked Dela Rosa to Duterte's war on drugs.

CCTV footage shown during the session captured dela Rosa running toward the session hall to evade NBI agents, who were wearing civilian clothes.

Senators later voted to cite the NBI personnel in contempt and place them under Senate custody.

Following the meeting with Matibag, however, Senate President Alan Peter Cayetano said they agreed that the contempt order against the nine agents would remain in effect while they stay under NBI custody.

Duterte is currently under ICC custody in relation to crimes against humanity charges over alleged killings during his time as Davao mayor and as president. — BAP, GMA News