Doctors restarted the hearts of two runners after they suffered cardiac arrests during a marathon on Sunday in Guangzhou, the capital of Guangdong province.

"Both runners, 20 and 30 years old respectively, are undergoing further treatment (in hospital)," said Tang Xiaoping, director of the medical service department of the marathon's organizing committee.

The organizer did not give the names of the runners, but said they were Chinese.

"As the marathon is a really challenging event, we urged participants to pay more importance to their condition," Tang said.

The runners suffered cardiac arrests after they crossed the finish line of the 10 km and 5 km races, Tang said.

The event featured full and half marathons as well as 5 km and 10 km races.

"Their (the competitors') hearts started beating again shortly after receiving emergency treatment. They were then sent to nearby hospitals," Tang said.

To ensure the smooth running of the event, the organizers had arranged up to 250 medical staff and 20 ambulances along the route of the race, which passed major landmarks in Guangzhou.

According to Tang, most of the participants were not professional runners, and the oldest was 78.

"Up to 900 runners developed symptoms such as being sick, dizzy or cramped," Tang said.

The marathon, the first of its kind in Guangzhou, attracted more than 20,000 Chinese and overseas runners. About 40 professional athletes from Africa took part.

Ethiopian Bekana Daba Tolesa won the men's full marathon in 2 hr, 11 min and five sec. He won the Houston Marathon in 2011. Mulu Seboka Seyfu, also from Ethiopia, claimed the women's title.

qiuquanlin@chinadaily.com.cn