"It's so fast!" said Hong Kong resident Leung Shing, as high-speed train G5736 pulled into the Shenzhen North Railway Station in Guangdong Province on the Chinese mainland Sunday morning.

High-speed train G5736, named Vibrant Express, departed from the Hong Kong West Kowloon Station, terminus to the Guangzhou-Shenzhen-Hong Kong Express Rail Link, at 7 a.m. local time Sunday when the whole line of the rail link officially started operation.

Some 500 passengers, including those from media, came to the Hong Kong West Kowloon Station to take the first train. The carriage is quite spacious and the seats can be adjusted to face front or back.

In less than 20 minutes, the bullet train arrived at Shenzhen North Railway Station. Leung, who could not wait for his next ride, told the reporters that he was so excited for this historic moment that Hong Kong became part of China's high-speed rail network.

Seventy-year-old Leung woke up in the wee hours on Sunday and hurried to the Hong Kong West Kowloon Station to do the check-in.

The West Kowloon Station was open at 5 a.m., one hour earlier than usual, to welcome the first batch of passengers. Customs counters started to serve at 6:15 a.m., 15 minutes ahead of schedule.

The station was swarmed with people after opening. Passengers rushed to get their tickets, with some of them seizing this precious opportunity to take pictures before boarding the train.

Over 230,000 tickets have been sold thus far, according to Frank Chan, secretary for transport and housing of China's Hong Kong Special Administrative Region (SAR) government on Saturday.

The service of the Hong Kong section high-speed rail follows the same real-name ticketing system as on the mainland. With their tickets and personal identity document ready, passengers passed through the identity check at the ticketing concourse on level B1, followed by security check.

Passengers then went to the departure concourse on Level B3 to complete both the Hong Kong and mainland clearance procedures in one go.

Station assistants in navy blue uniforms were around to offer help when passengers had problems in doing ID checks or were not sure what to do next.

Sunny Tsui and her family were among the first batch of passengers on the debut ride. "I hope that my child can learn more about the development of the motherland," Tsui said.

On level B4, high-speed train Vibrant Express, a silvery train with white and red waves on both sides of each carriage, was at the platform waiting for passengers.

Mainland resident Jiang Zhihao was a big fan of high-speed train. To join this special journey, he flew all the way from from Shanghai to Shenzhen on Saturday evening, then entered the Hong Kong SAR through the land boundary control point.

"Besides of riding on the Vibrant Express, I also want to experience the convenience of co-location arrangement," said Jiang, who arrived the West Kowloon Station at around 4 a.m. local time.

Co-location arrangement has been applied at West Kowloon Station to speed up cross-border passengers' journey. Both Hong Kong and the Chinese mainland port areas have been set up at the station.

The 141-km Guangzhou-Shenzhen-Hong Kong Express Rail Link includes 115 km on the mainland and 26 km in the Hong Kong SAR.

Being a key part of China's high-speed rail network, it will offer direct rail services between Hong Kong and 44 destinations on the mainland, among which 38 to be long-haul, including Beijing and Shanghai.

"The ride is so smooth," said Jiang, who was looking forward to his next high-speed railway journey.