GREENE – A local man was arrested Saturday night, accused of throwing two rocks through a store window and then threatening a customer with a knife in the parking lot.

Eric Laroche, 21, of 504 Quaker Ridge Road, was arrested on several charges, but only after police tracked him down based on witness accounts of the incident.

Laroche was arrested on two counts of aggravated criminal mischief, a charge of criminal threatening and two counts of assault.

Police said the rocks were hurled with so much force through the windows of Landry’s Quick Stop that store employees and customers thought someone had fired a gun.

“They thought the store was being shot at,” said Maine State Police Trooper Ricci Cote. “A couple of them actually ran out back and into a walk-in cooler.”

Glass from the double-pane windows struck a clerk and a customer, though neither was badly hurt. The first rock nearly struck one of the employees, police said.

“The suspect then yelled vulgarities at the clerk and threw a second rock,” Cote said.

A store customer tried to stop the suspect in the parking lot, but Cote said Laroche pulled a knife on the man. The suspect then fled the area, leaving behind $2,000 worth of damage to the building as well as a store filled with shaken customers.

Police called to the area did not have much to work with. Store surveillance cameras were not working at the time of the incident. Customers huddled together in the store did not come up with a plate number of the car the suspect drove off in.

“The people at the store told me he appeared spaced out,” Cote said. “… They were petrified of him.”

Cote got a description of the suspect and was preparing to call in a sketch artist to help with the investigation. Then portions of the description reminded him of an incident he had investigated a few days before.

In the earlier incident, Cote had been called out to Quaker Ridge Road for a report of a man who insisted he heard voices from the woods. When Cote went there, he said, he found Laroche, living with his parents and off medication used to treat a mental problem.

The description of the suspect from Landry’s matched that of Laroche, Cote remembered from the earlier incident.

When the trooper tracked Laroche down at his home, the hunch paid off. Laroche said he had been upset with a person at the store when he hurled the rocks through the window.

“He was upset with one of the female clerks,” Cote said.

Laroche told the trooper he believed the clerk had done something to a sandwich he had ordered at the store. Cote said there was no reason to believe that the sandwich had been tampered with.

Cote said he considered it crucial to track down the suspect as he began investigating the incident because of the lingering threat.

“The people at the store were afraid this guy might come back,” the trooper said. “I was very concerned about this guy and about finding him. Hopefully, he’ll get some help.”

Laroche remained at the Androscoggin County Jail in Auburn on Sunday.