PASAY — Gunfire rang out Wednesday night inside the Philippine Senate in Pasay as authorities attempted to arrest Senator Ronald dela Rosa under an International Criminal Court warrant. Dela Rosa remained in protective custody with allied senators as agents sought to detain him and possibly transfer him to the ICC.

Journalists ran for cover as the shots erupted minutes after soldiers carrying rifles and wearing protective gear went up the stairs of the legislative building. It was not immediately clear who fired the shots, whether anyone was injured, or what set off the gunfire. Military personnel, some carrying assault rifles, arrived inside the Senate building late Wednesday, and local media showed scenes of chaos.

Senate President Alan Peter Cayetano confirmed that building security had told him gunshots were fired inside the Senate. "The emotions are high here. This is the Senate of the Philippines and we are allegedly under attack." he said. In a video posted on Facebook from inside the building, he said he was willing to meet anyone who wished to serve an arrest warrant. "We don't know what's happening, everyone is locked in their rooms now, we cannot go out. We cannot secure our other staff." Cayetano also said: "What is happening? Why are we under attack here?"

The ICC unsealed an arrest warrant on Monday, dated November, charging dela Rosa with the crime against humanity of murder of no less than 32 persons between July 2016 and the end of April 2018. The charges mirror those faced by former President Rodrigo Duterte, who awaits trial in The Hague.

NBI agents tried to arrest dela Rosa on Monday, but he outran government agents through the Senate's hallways and staircases, reaching the plenary hall and seeking help from fellow senators. He has spent two nights in the Senate building in a standoff with authorities. Philippine law enforcement agents were earlier gathering outside the building, Senate Sergeant-at-Arms Mao Aplasca said.

A former police chief, dela Rosa urged President Ferdinand Marcos Jr on Tuesday not to hand him over to the ICC, denied involvement in illegal killings, and said he was ready to face justice at home. "I am appealing to you. I hope you can help me. Do not allow another Filipino to be brought to The Hague." he said. He also said: "I hope that, as the father of the nation, you will take care of all Filipinos. That is the role of government, to care for its people." Dela Rosa added: "Mr President, [you] may one day face a situation like this. You may also encounter problems, and then you will understand, you will feel what I am feeling right now." He further said: "I did everything for the country. I did not enrich myself. I worked faithfully."

Dela Rosa was Duterte's top lieutenant and oversaw an anti-drugs crackdown during which police say more than 6,000 suspected drug dealers were killed in official operations between July 2016 and April 2018. Thousands of drug users were also shot in slumland killings blamed on vigilantes or turf wars. Police say those killed during operations had resisted arrest and reject allegations of systematic murders and cover-ups.