▶ Watch Video: President Biden begins visits to South Korea, Japan Two Secret Service employees have been sent home from Seoul, South Korea, and placed on administrative leave after an off-duty incident in which one of the two had a physical “altercation” with a local taxi driver, sources familiar with the situation tell CBS News. The Secret Service employees, one a special agent and one a security specialist, arrived in Seoul as part of the advance team ahead of President Biden’s visit. The two went bar hopping Thursday night and returned to the Grand Hyatt Hotel, where the president is now staying. When one of the employees got into the physical “altercation” with the taxi driver, the Secret Service, hotel security and local police were contacted. Only one employee was investigated by local authorities, and no one was detained, arrested or charged with any criminal conduct. But after police interviewed the Secret Service employees, it was determined they should be sent home. The employees were sent back to the U.S. on a plane that departed at 4 p.m. local time in Seoul, less than an hour-and-a-half before Mr. Biden was scheduled to arrive. The two were immediately placed on administrative, leave, sources tell CBS News. The administration is investigating whether the two Secret Service employees were intoxicated, based on their behavior during the suspected alcohol-related incident, and not for the physical altercation. Only one of the two employees was involved in the altercation. U.S. Secret Service policy states that employees cannot have a drink 10 hours before they are scheduled for duty. For example, with a shift that begins at 9 a.m., the last sip of alcohol can be had at 10:59 p.m. This rule applies to both domestic and international trips, as well as regular day-to-day duties. “The Secret Service is aware of an off-duty incident involving two employees which may constitute potential policy violations,” Anthony Guglielmi, chief of communications for the Secret Service said. “The individuals will be immediately returned back to their post of duty and placed on administrative leave. There was no impact to the upcoming trip. We have very strict protocols and policies for all employees and we hold ourselves to the highest professional standards. Given this is an active administrative personnel matter, we are not in a position to comment further.” The Secret Service has not released the names of the employees. The president is in Seoul to kick off a five-day Asia trip to underscore the U.S. relationship with allies in the region in the face of China’s rise and concerns about North Korea’s nuclear weapons program. Kathryn Watson and Nicole Sganga contributed to this report.