Six armed robberies or attempted robberies have been reported, including five in the last two days.

Police investigators don't believe the string of robberies are related, but are looking for possible connections among the cases.

"We're looking at all of them for a connection, particularly where ski masks were used," said HPD Maj. Darryl Perry, commander of the department's Criminal Investigation Division. No one has been hurt in any of the robberies, but "anytime someone flashes or uses a handgun or another weapon in a crime, it's serious," Perry said.

At 12:40 this morning, three adult males approached a vehicle waiting at a stop sign at Kahakai Drive in Waikiki, when one of the men wearing a ski mask and dark clothes and gloves showed a silver semi-automatic handgun to the driver and demanded money.

The driver reversed his car to escape and the robbers left the area, police said.

Also this morning, a man robbed another man with a knife at 2:45 a.m. at a bank automated teller machine at 1580 Kapiolani Boulevard.

The victim, a man in his 30s, ran away, while the robber fled in a white SUV driven by a female.

The ATM robber is described as 5 feet 10, 250 pounds, with black hair and brown eyes. He wore a white and red long-sleeved shirt and black beret, police said.

Police are investigating four other robberies since Sunday:

• Two masked men used a gun to rob the Kailua Times Supermarket Monday evening of 50 cartons of cigarettes.

The two men entered the supermarket at 9:21 p.m. wearing black ski masks, police said. One of the men showed a small handgun to the cashiers, while the other man stuffed the cartons of cigarettes into a brown garbage bag.

• A man robbed a Pearl City gas station at 6:15 a.m. yesterday, entering the Chevron station at 777 Kamehameha Highway with a handgun and demanding money, police said. He ran off with an unknown amount of cash.

• At 10:39 p.m. Monday, three men armed with brass knuckles and a baseball bat confronted a group of six people outside the Mililani Jack in the Box restaurant, demanding money and CDs. When the group refused, one of the men smashed the rear windshield of a victim's car, police said. The men fled the scene when they realized police had been called.