The first ghostwriter was detained during the Chinese language test on Sunday morning at Nanchang No. 10 Middle School in Jiangxi province.
Cao Zhenglong is head of the provincial Education and Examination Authority.
"It's less than 20 minutes before the exam ends. We took action with local police and put the suspect surnamed Li under control. Li has acknowledged that he was a stand-in test taker. "
An anonymous worker with the school says the man showed an authentic document when he passed the security checkpoint.
"He's using an authentic identity card. What can you do about that? You have to understand our situation, he's using a real document and the photo looks like him. It's such an important exam that we could not do anything to him easily. We can only doubt. What else can we do?"
Xiong Biao, director of the Nanchang Examination Institute, says an investigation is under way.
"We have a strict review process and methods. Every link in the process is overseen by someone. We will handle this case appropriately by our rules and laws, no matter which link broke. We are investigating the matter right now."
In the afternoon, another person was caught taking the exam under someone else's name in Yingtan, another city in the province.
The second stand-in has not been unidentified.
The raids came on the heels of a report by Guangdong-based Southern Metropolis Daily.
The newspaper revealed via its Weibo account that one of its reporters had infiltrated a fraud gang that hires university students to take the two-day exam for "clients".
The report says the hired test takers produced a fake ID at the exam venue and can be paid up to 70-thousand yuan, or over 11-thousand US dollars, for a high score.
The undercover reporter pinpoints the ghostwriters as several college students from Hubei province.
The Ministry of Education says it has asked the public security ministry to oversee the investigation and that cheating in Gaokao could amount to a punishable crime in serious cases.
It says students who hire others to take the tests for them will be disqualified from the exam and their test takers will be expelled.
The Gaokao is often referred to as a "battle to determine fate".
Because the stakes are high, cheating is a recurring problem.
About 9.4 million Chinese high school graduates, slightly less than the population of Sweden, sit for this year's exam.
They are vying for about 7-million spaces in Chinese colleges and universities.
For CRI, I'm Liu Kun.