South Korean investigators entered the presidential residence to arrest Yoon Suk Yol. Hardliners gathered outside the building to defend the leader, AFP reported.
Investigators from the Corruption Investigation Office (COI), which is probing Yun's short-lived declaration of martial law, were let through heavy security barricades to enter the residence.
Yun, who has already been suspended from office by lawmakers, will become the first sitting president in South Korean history to be arrested.
Senior SRK prosecutor Lee Dae-hwan was seen entering the compound with other officials.
Dozens of police buses and hundreds of uniformed officers lined the street outside the complex in downtown Seoul.
About 2,700 police officers and 135 police buses were deployed in the area to prevent clashes.
Yun has holed up in the residence since the court approved his detention order earlier this week, vowing to "fight" authorities who want to question him over his failed attempt to impose martial law.
The president issued an erroneous declaration on 3 December that led to his impeachment and leaves him facing arrest, imprisonment or, at worst, the death penalty.
It was unclear whether the presidential security service, which still protects Yun as the country's acting head of state, would carry out investigators' orders.
Members of his security team have previously blocked attempts by police to search his presidential residence. | BGNES
