LOS ANGELES, July 22 -- A spokesman for 2015 Special Olympics World Summer Games (SOWG) on Wednesday blamed factors including serious delays of flights for the ordeal that about 1, 000 of the athletes went through for the first night upon their arrival in Los Angeles, California.

An estimated 6,500 athletes with intellectual disabilities and 2,000 coaches representing 165 countries and regions will be taking part in SOWG from July 25 to Aug. 2. It is the largest sporting event in Los Angeles since the city hosted the 1984 Olympic Games. And opening ceremonies for the world's biggest sport games are scheduled for Saturday at Los Angeles Memorial Coliseum.

As the world's largest humanitarian event, the SOWG in Los Angeles got a rocky start.

Tuesday turned out to be the toughest day for the ill-prepared organizers, as 6,000 athletes, coaches and staffs from 120 foreign teams all arrived in Los Angeles.

What more than 1,000 of the SOWG athletes of several foreign teams didn't expect was that after they traveled far from China, Peru and Europe and landed in Los Angeles airport Tuesday night, they had to wait several more hours for buses and registration.

When the registration in the Welcome Center finished, the teams were told no buses were available to send athletes to the hotels as bus drivers did not reach agreement with the organizing committee on overtime working. In the end, the athletes had to sleep on the floor of the Welcome Center in Loyola Marymount University for the night, their first in Los Angeles.

"But we had serious flight delays, delays of transportation, and delays in the data processing here in the Welcome Center, so some of the delegations were put up behind schedule," SOWG spokesman Rich Perelman told Xinhua.

"Approximately 7,200 people came in to the Welcome Center in Loyola Marymount University (LMU) yesterday to be processed for registration before they could go to their host towns," said Perelman, referring to the workload. "About 80 percent of them were processed and they went to their host towns exactly the way they were supposed to."

He said according to the California law, bus drivers have certain daily working time. As there were no available buses to send the delayed delegates, they had to stay overnight at the Welcome Center.

The Red Cross was brought in to the Welcome Center, a gym of the university, to distribute blankets, water and snacks. And a special breakfast was provided to the athletes who were still in the gym in the morning, Perelman said.

Athletes and coaches from China, Norway, Mexico and England were among those left stranded at the LMU Welcome Center.

The Chines team had to wait four hours for buses to transport athletes from the airport to the Welcome Center, which is located at the Gersten Pavilion of Loyola Marymount University, a 15 minutes' drive from the airport. When the registration in the Welcome Center finished, the team was told no bus was available to send athletes to the hotel, according to Chinese team leader Zhao Qian.

Chinese Consulate in Los Angeles eventually moved in to coordinate by hiring more than 30 taxis to carry the Chinese team to their hotel. It took nine hours for the 129-member Chinese delegation to arrive their hotel in Long Beach after getting off their plane at Los Angeles International Airport.

Chinese team leader Zhao Qian told Xinhua on early morning Wednesday in the Welcome Center while waiting for transportation that Chinese athletes were still optimistic and did not complain. They even did not forget to sing a birthday song to a team member as a kind of celebration.