Clerks at two adjacent Jewel Lake businesses reported being accosted by a man Monday wielding a knife and wearing a cardboard box on his head during a robbery and an attempted robbery under investigation by Anchorage police.

Investigators haven't conclusively determined that the suspects reported at the Big Mike's Tesoro gas station and Value Liquor, both on Jewel Lake Road, were the same person.

"It's a possibility that we are considering," police spokeswoman Renee Oistad said in an email Thursday.

No injuries from either incident were reported, police said. The first robbery was called in from the Tesoro station at about 2:45 p.m. Monday.

"The clerk stated a man entered the gas station wearing a box on his head, produced a knife, and demanded items from her," Oistad wrote. "The suspect left on foot with an undisclosed amount of money and cigarettes."

Kevin Wright, manager of the Tesoro's repair shop, said his girlfriend was behind the counter at the time.

"Some goofball wearing a cardboard box on his head with two eye holes punched out came in and threatened her," Wright said. "There was a customer in the store that he didn't see, who was already calling 911."

The second incident, at the nearby Value Liquor store, took place just before 9 p.m. The suspect in that case had entered the store and waved a knife at an employee.

"Initially there were no other customers in the store, but after the suspect brandished the knife, another male customer walked in and told the suspect to leave," Oistad wrote. "The suspect left without taking anything."

Rebecca Mercado, a manager at the Value Liquor, said the store had also been robbed in January 2016. The robbery attempt Monday was over in about a minute, she said.

In both cases Monday, police said, the suspect left on foot. The K-9 unit attempted to track the suspect from Value Liquor but failed to find anyone, and no arrests had been made as of Thursday.

The Tesoro station, repair shop and a car-rental business under the same ownership at the site had about half a dozen people between them at the time of the robbery, Wright said. None of the businesses had been robbed in recent memory.

"Middle of the day, all us guys here, they really lucked out," Wright said. "That was our first time in years and years — just stupid people doing stupid things."

Mercado said upgrades to Value Liquor's security system were being considered in the wake of Monday's incident.

"There's a lot of weird people in this neighborhood," Mercado said.