NIAGARA FALLS - An alert Niagara Falls police officer noticed something was not right when he drove by a 7-Eleven convenience store around midnight Wednesday, so he drove back around to check and was able to break up an armed robbery in progress at the store in the 9100 block of Niagara Falls Boulevard.

"The suspect, who appeared to be talking with the store clerk, was wearing a black Carhart hoodie jacket with the hood worn up. I know that most of the evening store clerks in the area request or require that anyone entering the store take off or lower their jacket hoods," Officer Walter Nichols reported.

Nichols said he decided to circle around, take a second look and see if anything bad was going on.

The clerk later told police that a man had entered the store and was acting suspiciously, walking around but not buying anything, and was appearing to be stalling for time, waiting for the store to empty. The clerk said that when the last person left the store , the man approached the counter and pulled what appeared to be a black semiautomatic pistol from his waistband.

The clerk told police the man demanded that he empty both drawers and hand over all his cash.

The clerk said he told the man: "You're out of your mind. A police car just entered the parking lot."

The clerk then knocked on the store window and started waving to Nichols, who had just returned to the scene.

When the robber saw the approaching marked patrol car, he fled empty-handed.

Nichols said he followed him north across Niagara Falls Boulevard and was able to get a good look at his face because he kept looking over his shoulder as he ran. Nichols lost sight of him behind the nearby Cayuga Village trailer park.

A perimeter was set up by responding officers, and K-9 units were called to the scene. No suspects were located, but evidence was recovered from the scene, as well as from the store security video.

Nichols described the robber as age 19 to early 20s, about 5-feet, 8-inches tall, with a medium build, wearing a black hoodie-type jacket with a red-colored shirt underneath, blue jeans, black baseball cap with a red brim; he appeared to be clean-shaven with short hair. The clerk confirmed the description.

Niagara Falls Police Superintendent John R. Chella called the incident "proactive policing."

"For as many years as I have known Walt, he has had a great attitude about policing," Chella said.

"He didn't just happen to be in the right place at the right time. He was checking his beat and businesses. And he was observant about policies. He knew the 7-Eleven policy, and that was the first thing he noticed. That's clear thinking."

Niagara Falls has recently seen a rash of 7-Eleven robberies. Last week, detectives charged Paul J. Schubert, 21, of Garden Avenue, for his alleged role in two robberies and one attempted robbery of three 7-Eleven stores. He is held without bail in Niagara County Jail.

Schubert is charged with robbing a 7-Eleven store at 6802 Buffalo Ave. Sept. 12. On Sept. 6, he allegedly attempted to rob a store at 7610 Buffalo Ave. and, when he didn't succeed, he robbed a store at 2620 Niagara St. less than two hours later, police said.