Police were investigating three bank robberies on O'ahu that occurred within about an hour of each other yesterday afternoon.

The first robbery occurred at about 4:35 p.m. at the Kapi'olani Boulevard branch of Bank of Hawaii. Police said a man showed a teller a handgun and demanded money.

The man then reached over the counter and grabbed an undisclosed amount of cash, police said. The man was last seen running toward Ala Moana Center.

At about 5:20 p.m., a man wearing a stocking over his face demanded money from a teller at the Central Pacific Bank's Kalihi branch. He was given some cash and fled.

At 5:48 p.m., a man entered the Mililani branch of American Savings Bank and demanded money from a teller. The man, who was wearing a fake beard and showed a pocketknife, was given some cash and left on foot.

Police said the description of the suspects in the Kalihi and Mililani robberies were similar, but did not say if they believed the same man committed both crimes. Police did say that the man who robbed the Bank of Hawaii may have been involved in other robberies in the Ala Moana area.

Reach Curtis Lum at culum@honoluluadvertiser.com.