South Korean authorities failed to arrest impeached President Yoon Suk Yeol on Friday over his martial law declaration, after evading a crowd of protesters outside his compound but coming to a standoff with presidential security forces inside.

Yoon supporters gathered in the pre-dawn hours near the presidential residence, with the numbers swelling into the hundreds as they vowed to block any attempt to arrest Yoon.

Officials from the Corruption Investigation Office for High-ranking Officials (CIO), which is leading a joint team of investigators into Yoon’s brief declaration of martial law on Dec. 3, arrived at the gates of the presidential compound shortly after 7 a.m. (2200 GMT Thursday) and entered on foot.

Once inside the compound, the CIO and accompanying police

faced cordons of Presidential Security Service (PSS) personnel, as well as military troops seconded to presidential security, media reported. South Korea’s Ministry of National Defense said the troops were under the control of the PSS.

The CIO called off the effort to arrest Yoon around 1:30 p.m. due to concerns over the safety of its personnel due to obstruction, and said it “deeply regretted” Yoon’s attitude of non-compliance.

“It was judged that it was virtually impossible to execute the arrest warrant due to the ongoing standoff,” the CIO said in a statement.

Yoon’s lawyer said in an earlier statement on Friday that execution of an invalid arrest warrant against Yoon is unlawful, and that they would take legal action, without elaborating.

The arrest warrant, approved by a court on Tuesday after Yoon ignored multiple summons to appear for questioning, is viable until Jan. 6, and gives investigators only 48 hours to hold Yoon after he is arrested. Investigators must then decide whether to request a detention warrant or release him.

The CIO said on Friday it would review the situation and decide on possible next steps.