Suspected robbers broke into Equity Bank, Kayole Branch, on Saturday and stole an unknown amount of money.
The suspects are said to have gained access by drilling a hole into a wall leading to the bank’s safe.
Police said they took away an ATM machine containing money and the safe.
Detectives from Kayole CID visited the scene on Sunday but are yet to make arrests.
It is also yet to be established how the suspects managed to disable the bank’s CCTV and alarm systems.
Furthermore, none of the security guards manning the bank knew about the incident until Sunday morning.
Police suspect that the theft was organised with the help of bank staff.
Bank officials are yet to record statements with the police. Police sources said the bank staff asked for more time to reconcile their books to establish how much money was lost.
Last year thugs, posing as Equity Bank auditors, stole Sh30 million from the Othaya branch in Nyeri county.
The three armed robbers arrived at 6.50am and identified themselves as auditors from Equity Nairobi branch, said Central Regional Police Commander Larry Kieng.
Kieng the said security guards allowed the men entry “since they showed their fake badges”.
“When the men entered the bank, they drew a knife and ordered the guards to lie down as they stashed the money into three sacks,” he said.
Kieng said the robbers escaped using the back door.
Three suspects were arrested and charged with the robbery.