As the Seoul Nuclear Security Summit kicked off Monday, traffic in parts of the city was brought to a standstill as officials locked down roads for delegates making their way around the city.

According to the Seoul Metropolitan Government, only 61 percent of citizens took part in rotational driving during the morning commute on Monday, as Korea’s biggest-ever diplomatic event kicked off.

Seoul is host to leaders and representatives from 53 countries and four international organizations until Tuesday during which respective motorcades are expected to move throughout the city.

Seoul City officials asked drivers to leave cars with license plate ending in odd numbers at home on Monday and those with even numbers on Tuesday.

However officials reported that for the most part, traffic throughout the city reflected a normal Monday morning commute.

Police officials also reported that major roads were clear Monday morning in the Gangnam District, including Olympic-daero and Gangbyun-bukro.

Police reported that traffic built up on the Inner Circulated Road and the Dongbu Expressway.

According to officials, the lack of traffic within the city is thought to be attributed to most leaders arriving on Sunday, and roadblocks being sparsely set up throughout the city.

Near the summit main venue COEX, traffic flow was slower than normal. Vehicles took 20 minutes crossing over the Yeongdong-daegyo during noon on Monday.

And as of 3 p.m. on Monday, traffic was at a standstill near major areas where representatives were expected to pass including the COEX Center and areas near Gwanghwamun.

Seoul officials believe that traffic will be at its worst on Tuesday, as motorcades amass at the venue.

Officials estimate that some roadblocks may be in place for up to two hours on Tuesday during rush hour, and have urged for the cooperation of its citizens.

“There is a chance that the streets could be turned into parking lots tomorrow (Tuesday) as the city faces the largest scale of roadblocks it has ever seen,” said a city official, who declined to be named.

“We ask for the cooperation of citizens in taking part in the rotational driving and utilizing public transportation.”

By Robert Lee (robert@heraldcorp.com)