SEOUL, An unidentified person called about 20 taxis to the presidential residence in central Seoul early Monday morning, prompting the police to open an investigation. According to the Yongsan Police Station, the taxis arrived near the presidential residence in succession between 2:30 am. and 4:20 a.m. in response to the individual's calls. The person did not appear for the taxis. Stopped by police officials guarding the compound, the taxi drivers said they had been called. Police said the individual appears to have hailed the taxis using an application, setting his departure point at a location near the presidential residence. The telephone number the person provided in the application does not exist, officials said. Police launched their investigation into the person on charges of business obstruction and are currently tracking the individual while enhancing security around the presidential residence, officials said. Source: Yonhap News Agency