Three of them were arrested and then fired, along with the fourth person who was not arrested, the BBC reported.
The bribe sums amounted to "tens of thousands of yuan" (thousands of dollars), Baidu spokeswoman Betty Tian told the British news network.
Dubbed the Great Firewall and controlling almost 80 percent of China's online search market, Baidu bans a number of foreign Web services and imposes strict censorship and self-censorship rules.
"Baidu has always firmly cracked down on the illegal behavior of online posts deletion for payment," Tian said in an e-mail to the BBC.
"Baidu has also proactively reported actions involving illegal behavior to the public security organs.
"Baidu has continuously provided professional ethics education to staff members who are given authority to delete online posts."