A 45-year-old man drove his excavator into the country's top prosecution building in Seoul on Tuesday, injuring a security guard and destroying facilities, police said.

The construction vehicle rammed into the Supreme Prosecutors'Office at around 8:20 a.m., according to police.

The guard, 60, was injured while attempting to stop the vehicle by firing a gas gun and was rushed to a nearby hospital.

The entrance door of the building, as well as other facilities, were destroyed in the process.

The driver, identified only by his surname Chung, was arrested by police on site.

He left from Sunchang, some 360 kilometers south of Seoul, at around 3 a.m. with the excavator on a truck, according to police.

He left the truck near the prosecution office and passed through the front gate with the heavy vehicle.

During a police interrogation, he said he committed the crime "to help Choi Soon-sil die as she said she committed a sin that deserves death."

Choi is a confidante of President Park Geun-hye, who is at the center of a political scandal that is rocking the country.

On Monday, she appeared for questioning at the Seoul Central District Prosecutors' Office, located across the street from where the ramming incident took place.

Entering the prosecutors' office, she said she has "committed a sin that deserves death."

Her lawyer later said she was just trying to express her feelings, adding the comment does not hold any legal meaning.

After she entered the office, a 43-year-old man, identified only by his surname Park, threw sewage at the district prosecutors' office. He was also immediately arrested on site. (Yonhap)