At least 10 gunshots rang out inside the Senate of the Philippines on Wednesday night, May 13, as the upper chamber was placed under a total lockdown and personnel from the Office of the Sergeant-at-Arms (OSAA) ordered reporters and Senate staff to clear the second floor of the building.

Senate Sergeant-At-Arms Mao Aplasca told reporters that an arrest was about to be carried out inside the Senate premises but did not name the senator involved. "They are going to arrest," Aplasca said.

“No arrest can happen inside the [premises]. If there will be arrest, it will be by virtue or order of a local court,” Sergeant-at-Arms Mao Aplasca also told reporters.

Dela Rosa, a former chief of the Philippine National Police and the subject of an International Criminal Court (ICC) arrest warrant in connection with the Duterte administration's war on drugs, has remained inside the Senate complex since Monday under the Senate’s protective custody. His whereabouts following the shooting were not immediately known.

Earlier in the day, during his Facebook livestream, Dela Rosa called on members of the Armed Forces to push back against any move to surrender him to foreign authorities, urging former colleagues in uniform to make their position known.

SP Alan Peter Cayetano confirms gunshots

In a Facebook Live broadcast aired from inside the Senate, Senate President Alan Peter Cayetano confirmed the gunshots and said senators in the building were "allegedly under attack."

Cayetano said Senate President Pro Tempore Loren Legarda and his sister, Sen. Pia Cayetano, were able to reach National Bureau of Investigation (NBI) Director Melvin Matibag by phone during the lockdown. According to the Senate President, Matibag told the two senators that no NBI agents were inside the Senate and that the bureau had been instructed to stay away from the premises.

The Senate President added that four senators received tips while in a meeting that they should leave the area because "something was going to happen."

"The emotions are high here dahil bakit kami paalisin eh we're waiting for the Articles of Impeachment and we're having a meeting," Cayetano said. "Kung sino ang nakikinig from the government, this is the Senate of the Philippines, we are allegedly under attack."

Sen. Robin Padilla was also seen telling reporters to evacuate the Senate premises but declined to provide further details.

Armed members of the Philippine Marines were earlier observed entering the Senate building shortly after the lockdown took effect.

Meanwhile, the National Union of Journalists of the Philippines (NUJP) said it was monitoring the situation, confirming that reporters had been ordered to exit the Senate but that several media workers remained stranded inside the building. The group's Media Safety Office advised newsrooms to prioritize the safety of journalists on the ground, urging them to drop to the floor during gunfire and move to a safe area before filing reports.

Remulla arrives to 'secure,' not arrest

Department of the Interior and Local Government (DILG) Secretary Juanito Victor "Jonvic" Remulla arrived at the Senate. The DILG chief told reporters that his top priority was the safety of the senators inside the building.

Based on an initial report he received, Remulla said no one had been hurt in the incident. The identity of those responsible for the gunfire, however, had yet to be established.

Articles of impeachment arrive mid-lockdown

In the middle of the lockdown, the Articles of Impeachment against Vice President Sara Duterte were formally transmitted to the Senate. House Secretary General Atty. Cheloy Velicaria-Garafil handed over the documents to Senate Secretary Mark Leandro "Dong" Mendoza at exactly 7:22 PM, just minutes after the lockdown was imposed.

"The transmittal of the Articles of Impeachment marks the beginning of the next constitutional phase of the process, and the House Secretariat made sure that all records were complete and in proper order prior to submission," Garafil said in a statement.

The Vice President was impeached for the second time by the House of Representatives on Monday, May 11, on a 257-25-9 vote, making her the first official in Philippine history to face impeachment twice.

This is a developing story.