Honolulu police are investigating an armed robbery involving a masked suspect at the 7-Eleven convenience store in Nuuanu early Tuesday.

This is the third armed robbery to occur at a 7-Eleven store on Oahu in two days.

Police said a man wearing a mask entered the convenience store on the corner of Nuuanu Avenue and N. School Street at approximately 4 a.m. today. He allegedly approached a store employee, brandished a pistol and demanded money.

Police said he fled with an unknown amount of cash.

No injuries were reported.

Police suspect the robbery is related to two armed robberies at 7-Eleven stores in Moiliili and Waialae-Kahala early Monday.

The robbery in Moiliili occurred at about 3:10 a.m. and the robbery in Waialae-Kahala occurred at 5:45 a.m.

Both cases involved a masked suspect armed with a handgun.